Someone started a thread on this very question in the bashers forum (of all places).I think there are three reasons the guys might have voted for Christy:
1) Deena won immunity, so they couldn't target the strongest female. So they went for the 2d strongest and most competitive female, thinking that Heidi and Jenna are weak contestants to be waxed later.
2) They were thinking with their little heads, wanting to keep the Cute-Girls-Who-Like-To-Strip over Christy.
3) Instinctive reaction to Christy's deafness. (and no, this is not a defense of them). I can see Roger leading the way on that score.
Contradictions don't exist. If you are faced with a contradiction, check your premises. You will find that one of them is wrong. -- Ayn Rand, Atlas Shrugged