I am the Creationist that this question refers to, that answered the original question.
Like most people, I have a revered respect for operational science, also called observational science. Experiments and observational science can be repeated in every laboratory in the world, confirmed, proven, observed over and over. This is how we develop facts of foundational importance, when multiple scientists get the same result through rigorous testing and the Scientific Method.
But nobody can observe evolution or Noah's Flood. Nobody can repeat an experiment called "The Grand Canyon." So there is a rather NEW branch of science called "historical science" that attempts to recreate the past without the involvement of God or scripture, in fact, historical scientists MUST find an alternative answer to scripture. This is the beginning of a new historical scientist, not Scientific Method, zero, that began the theory of evolution and rewrote history to their liking, whatever they want. Since nobody can prove or disprove it, it continues. Of course, there is a seed of truth in every lie, or nobody would listen. But it takes pages and pages of material to even show and explain their deeply buried presumptions, and uncover and disprove their many failed attempts at obfuscation. Darwinian Evolution is a lie, clear and simple. These are the "scientists" that creationists deplore, but then we deplore any liar, unlike your average secular person that tends to live comfortably with a mess of lies their entire lives w/o questioning their "facts" learned in school, repeated over and over in the media and print, perpetuating a life of lies.
Evolution needs millions/billions of years in order to be "possible." Nobody else needs millions/billions of years. But a probability is always based on “priors. Before you can find a probability that’s an actual number, you need to know something about the priors. You may have a tiny, non-zero probability, but if it’s based on priors that are themselves impossible, then the event itself may also be impossible. You can generalize the priors a lot, but you can never quite get rid of all of them, even though the evolutionist tries and hides them and refuses to make them foundational and open. This is not an irrational request; necessary for truth.
Given an infinitely large universe that’s more or less homogeneous (not empty but lots of stuff), then pretty much anything that’s remotely possible, that could conceivably be the result of a string of remotely possible causes (e.g., life), will happen somewhere. So, we can sit back and say things like, “well, there are X many possible arrangements of atoms, or quantum states, or whatever, and this is one of them…” and can then calculate a ball-park estimate of the probability of life occurring by chance; an incredibly small number of probability, but possible, at least according to what you're taught in school and over and over in the media according to the humanist curriculum.
Unfortunately, the answer we’d get would be incorrect, because the priors are messed up. While it could exist, it could NOT be "formed." So simply knowing that something is “possible” doesn’t mean that the universe can ever be in a state that would eventually lead to that thing happening. It's in these small omissions that makes Evolution a lie.
Radiometric Dating is useful for comparison of dates, but not for absolute dates. There is no accurate method for measuring millions/billions of years, period. It doesn't work. Take a sample rock to be dated and they'll ask where you found it and how deep. Without that, they can't fit it into their millions/billions of years timeline. They will refuse, can't be done.
The radioisotope methods, long touted as irrefutably dating the earth as countless millions of years old, have repeatedly failed to give reliable and meaningful absolute ages for Grand Canyon rocks.
Radioisotope Dating of Rocks in the Grand Canyon
https://answersingenesis.org/geology/radiometric-dating/radioisotope-dating-of-rocks-in-the-grand-canyon/
ICR's Grand Canyon Dating Project
http://www.talkorigins.org/faqs/icr-science.html
The data using Helium to date rocks actually confirms the young earth theory, if you care to look at the facts instead of holding fast to what you've been told (without the significance of the presumptions). The priors are messed up, but nobody can see that without a lot of work.
#6 Helium in Radioactive Rocks
https://answersingenesis.org/age-of-the-earth/6-helium-in-radioactive-rocks/
Helium Diffusion Rates Support Accelerated Nuclear Decay
https://answersingenesis.org/geology/radiometric-dating/helium-diffusion-rates-support-accelerated-nuclear-decay/
Absolute dating of rocks never works where/when tested for accuracy. Never. Not once. Not even close when we know the answer in advance. Yet when we don't know the age of the rocks, we are asked to believe that it does work. The priors are messed up, but nobody mentions those pesky presumptions.
The foundational Solar Nebular Theory of evolution doesn't work on any planet in our solar system; many of the planets shouldn't even exist according to this Theory. The priors are messed up (but they don't tell you that). Yet it is taken as fact when applied to Earth and everywhere else. Not anymore. It's a lie; eradicate it.
So now we come to the Grand Canyon. Because its northern rim, which includes the Kaibab Plateau through which the canyon is cut, is at a high elevation, the Colorado River as we know it today could not have carved the Grand Canyon. (After all, water doesn’t flow uphill, not even if allowed to try it for millions of years!). Look at a relief map; we all have the same evidences.
Geologists who accept the biblical history of the global Flood—maintain the Grand Canyon was carved by a sudden release of water dammed up behind the Kaibab uplift (aka Kaibab Upwarp). Creationist geologists believe this water was trapped in the aftermath of the global Flood.
In our observed past, just thirty years ago at the Mt. St. Helens eruption in 1980, it was a rather small event compared to the Grand Canyon
The events associated with the volcano’s explosion accomplished in hours, or just a few days, geologic work that normally would be interpreted as having taken hundreds or even millions of years. One particular canyon was formed, which has since been named the “Little Grand Canyon.” About 100 feet deep and somewhat wider, it is about 1/40th the scale of the mighty Grand Canyon. This canyon was formed in one day from a mudflow. A newly formed river then flowed through the Canyon formed by the mudflow.
I remember being taught in school that when you saw a canyon with a river running through it, you assumed that the river took a long time to erode the canyon. My teachers—not having known what happened at Mount St. Helens—would have concluded the same thing about the small river cutting through the Little Grand Canyon.
The evidence here shows that one can logically accept that the Flood of Noah’s day—and its after-effects—could have accomplished extraordinary geologic work, carving out canyons and the laying down of sediments in massive quantities all across the globe—just as we see today!
Increasingly, most geologists—evolutionist or creationist—who have been to the Grand Canyon will now acknowledge that the Canyon was carved by a lot of water over a little period of time, not over millions of years.
Grand Canyon Facts
https://answersingenesis.org/geology/grand-canyon-facts/
Edit:
Steve Austin, that did his Phd dissertation on coal formation coming from tree bark and not peat moss; proved it doesn't require 50,000 years to get coal from peat moss. What he saw as a grad student under a microscope was tree bark in these central US coal formations, with evidence of volcanic activity. He defended his thesis and predicted the entire aftermath of Mt. St. Helens; prior to the eruption. Steve found similar composition of stratigraphy in the Peat Moss (Tapeat?) layers of the Sauk rock unit of the Grand Canyon, laid down rapidly, not millions of years, by similar volcanic activity in evidence (to St. Helen). As you know, the Sauk covers at least half of the entire earth, a global event like Noah's Flood. Steve is a world renowned geologist that also happens to be a creationist.
Has anyone seen geologic layers forming over hundreds of thousands of years? No.
But isn't it powerful that the same features we've seen to form in hours? I have observation to back up my theory, evolution has nothing. Why would you believe nothing, a made-up story, over observational science? Because of a deep-seated investment/belief in a myth: millions/billions of years portrayed by the evolutionist/humanist/atheist curriculum/culture/cult.
Evolution is the biggest lie in the world today, taught as fact in our schools and universities; what a grave error and huge mistake; some sort of bad joke. I've been through it too. Difficult to about-face and realize what you were taught, paid $50,000 for the education/diploma, only to find out decades later that half of it was hocus-pocus myth; made-up bed-time stories. Like 40 yrs ago, it was Global Cooling. By 2030, all plant life was supposed to cease to exist. But now it's Global Warming, err, Climate Change, whatever. Without God and the Bible, we're pretty silly people. Nor can you believe in the Bible and Evolution both. You cannot fit millions of years in the Bible, nor in the true Geologic timeline for that matter. Where would you put them? You should re-study that presumption (prior); ridiculous, revealing.
So it all depends on your worldview. This isn't a debate about science vs. religion or the Bible, it's worldview vs. worldview.