It's my understanding that geologist use the surrounding strata to help date their fossil finds.
I think the point of the article is that that type of stone can form in a short time, and that it is not of the same age as the surrounding strata.
Limestone and other soft stones are easily eroded and redeposited.
I see no way that this shows the earth is about 6000 years old.
The tree ring sequence for the bristlecone pines of southeastern California is continuous past 12,000 years.