If they can get beyond the whole 'we don't believe that material could survive this long even under the best and rarest conditions' I will be surprised.
As with the past case, they never really provide any reason why this stuff couldn't survive if preserved in the way it is (largest and thickest bone, low moisture content of surrounding soil, low oxygen exposure).
If the inside of the bone is protected from water, chemicals, and microbes, there is no reason this isn't possible. What creationists can't explain is why exactly is it so rare when we find unfossilzed specimens of extinct mammals all the time.
If these remains are only a few thousand years old, why wouldn't we find more of them unfossilzed and in better condition.
Using this as an argument against the several independent lines of evidence that show us how old these fossils are is simply a poor argument. In the long run, take note if they don't back it up by more than 'we don't think it is possible'.
Let me know when they actually explain why it isn't possible.