Nah - it was me that christened him Neckbeard, but I have to admit it wasn't original. I read it somewhere as generic term for those "I'm a bloke, me, and that means I'm always right and should always be in charge" misogynistic, arrogant, tw*tty types.
I think it's because they a )always seem to have a beard, and b) often that beard grows right down their necks and joins their chest hair (though our Neckbeard's doesn't). It just seemed right for the lovely Mr Hepworth.