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To respond:
There is no research suggesting that preserved tissue remnants cannot last millions of years.
Boston Strangler Case: How Long Does DNA Last?
To reverse the question, if dinosaurs were just a few thousand years old, then all fossils ought to still contain dna, and we should be living in Jurassic Park. But of course every fossil we've ever found (which amounts to millions of bones) has long since been permineralized and has lost qualities of fresh bone material. With the exception of things like frozen mammoths and others of the like.
Also, in the article, there is consistent use of the word "remnants".
"Researchers have discovered what appear to be the
remnants of red blood cells and connective tissue in 75 million-year-old dinosaur fossils."
"in another fossil fragment, they found fibrous features with a banded structure
similar to that seen in modern-day collagen"
"The structures appear to be genuine
remnants of soft tissue; they are not fossilised."
Etc.
They're taking an ancient bone and doing their best to characterize it's qualities, despite it's old age.
If fossils were really just a few thousand years old, such a discussion wouldn't even be occuring as we would have long since sequenced dinosaur DNA and identified dinosaur proteins and really we would have a much better understanding of their cladistic relationships with one another.
Also, most laymen have trouble distinguishing dinosaur bone from rocks. Often they're exceptionally brittle as well, and can crumble in your hand like rotting wood. Whereas something like an egyption mummy from thousands of years ago sometimes still has things like dried skin and hair and is still largely articulated and complete. Which cannot be said for 99% of dinosaur finds.
So there is a pretty clear distinction between bones of the past 10,000 years, and dinosaur fossils or even fossils that are older than dinosaurs as well.