Men would rather be dead than caught wearing red velvet. Men would feel their masculinity threatened, having to be seen with all those elves. Men don't answer their mail. Men aren't interested in stockings unless somebody's wearing them. Finally, being responsible for Christmas would require commitment.
Cupid flies around carrying weapons.
Uncle Sam is a politician who likes to point fingers. Any one of these individuals could pass the testosterone screening test, but not St. Nick. Not a chance. Okay, painful though it may be, I must concede that the possibility of a guy Santa seems pretty remote. A myth is a myth, after all.