I feel it has a lot to do with what Federico said in the Diary Room on tonight's C4 show.
1. Despite all you Jon fans desperately wanting him out every week, he seems to be Jon's one ally in the house - I think he's probably the only housemate who has never nominated him (why I have no idea!

).
2. He's sick fed up of only housemates who speak up, voice an opinion on something (whether you agree with it or not), or dare to be a bit more boisterous than the others, being nominated and then evicted. Fed made a very valid point that a lot of the housemates are 'fireproof' because they're so bland (referring the likes of Gos, Nush and Steph).
My view, for what it's worth, is that he's totally disillusioned by the whole thing, and would rather leave than spend another however many weeks in a boring house where no-one dares to speak out of turn.
Shoot me down if you must - but that's what I think.
(And before you ask, Sticks .....
NO[/i], I DON'T fancy him!)
P.S. AND I think he was right about Tania supposedly breaking down after the nomination results were revealed - she was SO acting up for the cameras.