Your source is bogus.
Find a better one.
I am sorry but you can not just dismiss something like that without explaining why.
The main reason I would dismiss it, is that
(1) the opinion and rationale is based solely on what Dr Humphries says. Since you are not a geologist (neither is he) you are not qualified to actually figure out if what he is saying is true. Therefore he could be just saying God awful crap. One indicator of this, is whether he has any other non-biased scientists on his side.
(2) his rationale depends upon diffusion rates through a matrix of zircon, which could be anything, as evidenced by the fact that his result is
(3) he requires the coincidence of 6000 years to be a whoopie moment. However, if the figure came out at 15000 years, he would still be happy, and would most likely fudge the log axis on his graph.
(4) he and you are ignoring all the evidence which says the Earth is very old. It is not acceptable to dismiss all the valid evidence, and then consider only the incorrect evidence.
In science, it is good practice to consider the correct evidence. Evidence does not become correct, when it aligns with what you want it to be. You have to make a case that the majority of evidence is on your side, rather than fabricating it using woo. Even if the majority of evidence is on your side, you may still be wrong. It is generally not a good indicator, if hardly any evidence is on your side, and the only people who endorse your position are fruity.
Good luck with your quest to join random bits of incorrect conclusions into a half baked product.