The only thing that`s left is "the rabbits up there like to eat dead but freshly exposed moss"...or similar brilliant "reasoning".
So that's your explanation as to why there's not a 100-foot-thick carpet of undecayed dead moss? The rabbits ate the dead moss, but not the live moss?
It's good to be on the side of reason. I just have to point out that dead moss decays or gets munched by tiny bugs fairly quickly, as in within a few decades. Bacteria and bug eggs survive a deep freeze with no problems, and revive with every thaw.
And again, this whole denialist theory doesn't make sense. If there were other warm thawed-out periods, why didn't any moss grow at those times? This magical denialist moss not only doesn't ever decay, it also conveniently doesn't grow new moss, even when conditions are right for growth.