Remember when Sting "joined" the NWO a week before Uncensored 1997? He came out and stood beside them and it gave off the impression that he had finally made his decision as to which side to choose between WCW and the NWO. However, six days later at the PPV, he turned on them (one of the most epic wrestling moments ever) and let the world know that he was on WCW's side the whole time and never had any real loyalty to the New World Order.
This won't be quite as epic as that, of course, and it'll take more than a week before we get there (urm, maybe... I wouldn't be that shocked to see Bryan turn against them on the next Raw, honestly) but it's the same logic. Babyface joins a heel group and tries to make everyone think he's firmly on their side, but then at just the right moment, he turns on them to a huge pop. It gives Bryan something semi-interesting to do until the Rumble instead of what he'd be doing otherwise (i.e. talking constantly about winning the Rumble and not much else... as if that wouldn't get old after probably two weeks.)