That's the method of faith-based enterprises. They begin with an unsupported belief, and then proceed to hunt for evidence to support it, massaging the evidence to conform to their preconceived notion believed by faith. A faith-based confirmation bias allows in only that which is thought to be useful in supporting the faith-based notion while ignoring or denying the rest as you are doing here with radioisotope dating.
The proper method is to impartially examine the evidence first, all of it, and from that, derive a general rule that accounts for it all, then confirm that the rule has predictive power. That rule becomes a bona fide conclusion, since it was derived from the evidence after observing it. The faith-based method doesn't actually ever derive conclusions from evidence, but does try to feign that it has by arranging an argument where the unproven, faith-based premise is stuck at the end of the massaged evidence and presented as a conclusion derived from it - a pseudo-conclusion if you will.
I consider it wisest to get my science from scientists. I'll let them tell me what real science is. They do it professionally.
"You stare into your high definition plasma screen monitor in the comfort of your air conditioned home and in the glow of electric lighting, type into your cordless keyboard, then hit enter, which causes your computer to convert all that visual data into a binary signal that's processed by millions of precise circuits.
"This is then converted to a frequency modulated signal to reach your wireless router where it is then converted to light waves and sent along a large fiber optics cable to be processed by a super computer on a mass server, one of untold numbers of computers interconnected into a powerful network of intercommunicating computers bringing the world and all of its information to your laptop.
"This sends that bit you typed to a satellite orbiting the earth that was put there through the greatest feats of engineering and science, all so it could go back through a similar pathway to make it all the way here to my computer monitor 15,000 miles away from you just so you could express your disappointment in science and say, "Science is all a bunch of man made hogwash."- anon.
I've been criticized in the past for refusing to even open a creationist link, that being called the genetic fallacy (paraphrased, of course - not that term). I' admonished to consider the argument and not the source - evaluate the argument on its own merit.
The problem there is the dishonesty of these sources, and their proclivity for not presenting all of the relevant evidence. Sure, one can fact check what they do provide, but what about critical information such as that which you just added that negates the creationist argument, an argument that without that fact might be compelling. To fact check for that kind of omission pretty much means becoming familiar with everything there is to know on the subject including the information you provided. I can't see why I would bother myself to do that.
The problem, of course, is the ethics of creationist apologists. If they can't trusted, why even read their specious arguments?
I have another example of that from
DNA tests prove Darwin Was Wrong - Ape DNA very different from human DNA - Laws of Genetics Contradicts Ape to Human Evolution , with a Christian creationist arguing that "Man cannot have descended from a common ancestral great ape because all of the other apes have 24 pairs of chromosomes, and man but 23, implying the loss of a whole chromosome, which would be fatal.” Go ahead and evaluate that argument on its merits.
In that case, I happened to be aware of human chromosome 2 and could see the dishonesty immediately, but that was not true regarding C14. I don't know how long it would have taken me to find the key omitted facts.
So that is the justification for not even looking at or considering arguments from untrustworthy sources, and why it is not a genetic fallacy. I'm not arguing that the creationist's argument must be a lie if it comes from one of these sources, which would be the genetic fallacy, just that it very well might be, and I might not be able to determine just where the lie is.