>>723840521
Because he is an eternal manchild thanks to his immortality and being a perfect being from birth who had no reason to mature.

>>723840824
Jokes aside I don't think the mountain autism did much beyond giving him some slight magic resistance, which is reasonable enough.

But at one point Alice makes an offhand comment about it being impossible for him to reach a location as fast as he did implying it did something else, so they might have planned to wank it even harder.
But it's not like we will ever find out now.