I'm not really a Josie fan, but I do believe that she will go through with the deal!
IMO, she's not a 'bad lass', and realises that there's nothing to lose by buying Steve his hearts desire. On the contrary, it would only harm the publics perception of her if she gave back-word!...Not that I believe that this is the only reason that she will buy the leg!
As I said earlier, though I truly believe that Josie is 'the ultimate BB11 gameplayer', who's game was easily good enough to have won most of the BB series,....she is not a heartless individual, and would have helped Steve out even without the barrage of publicity that will erupt if there turns out to be a public handover organised by her publicist!
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Simply The Best!
Good job it's Big Brother!........Big Sister would be Evil!