Bottom line: They knew Cena was going to get a negative reaction, probably be booed out of the building (which he was) and needed someone to transfer the heat to. If they play their cards right, they could be building for a Cena heel turn, but if they do want to do it, they don't want to do it yet. I think that they want to establish Punk as a top babyface before turning Cena. This is partly why Cena didn't turn at SS. He's not going to have a match with Rock at TLC, and if he turns heel, he's got no one to feud with. It's unfortunate that they really don't mind screwing up Awesome Truth in the process, but they're handling Cena with kid gloves right now.
Of course, the obvious questions now are where Truth and Miz go from here, and where Cena goes from here. Truth and Miz likely have at least one match, but I think they really have no idea what to do with Cena right now and it's affecting the rest of the roster.