I lean towards "humans". And I nominate "humen" to be the plural form, as "humans" sounds weird.
Back on topic: I still find both 'nerd' and 'geek' to be offensive. Although I don't find "geek chic" to be offensive... probably because it has never been associated negatively - it has always been a label for a particular style, which in itself carries no meaning.
I think the guideline might be based on that "geek" has historically been a negative label, except where applied internally (as many negative labels do). So when paired with a non-existent or neutral phrase, it takes negative connotations, while when paired with a positive phrase it becomes a new "thing", and no longer holds the negative slant.