Dunno. How much pink snow do they have in your part of the world?
Camouflage doesn't have to be perfect. He may be a more successful snow hunter when his beard turns white. Women in general leave the hunting and war making to men so didn't need the added camouflage of a beard. I'm just bringing up the possibility. War and hunting advantages have had a significant influence on human evolution. That makes me wonder if the conventional skin color theory isn't the whole story.