It's not just the moly, it's across the board not redline. And yes metals have a useful life, I doubt moly is different. An example you might want to look at is calcium, at the end of a oci it is just about useless but the level is still read by the machine that reads uoa's. Even if moly was "worn" to be less effective, you would still see that level. Not only are all the levels off, the magnesium level is high compared to zero, redline doesn't even use magnesium, there is only hints of mag in redline uoa's.
The fact is across the board it isn't redline, there is not much more to say on it.
Mag is from gasoline - read here:
https://www.blackstone-labs.com/report-explanation.php