Would be pretty weird don't you think? A guy the fans won't boo helping the top heel win.
Not really no as he just got AA'd by Cena so he will want to avenge that and what bigger way than screwing Cena?
Perfect scenario for me would be there's a ref bump towards the end of the match, Cena hits his finisher on Miz and out comes Rock to make the count but pauses at 2. They have the usual confrontation which gives Miz enough time to recover, hit his finisher and count the three for Miz. He can then Rock Bottom Miz just to emphasise he is still face.
Most likely fantasy booking, but if he doesn't seek revenge and cost Cena at Mania then I will be MASSIVELY dissapointed.