The UFC needs to do everything they can to ensure Georges St-Pierre comes back healthy, wealthy, and wise. "Rush"ing him back into action because of this Nick Diaz pissing bong water (part II) is a huge mistake and could cause GSP problems. Now if he is really healthy, yes, he should come back. But the back-up plan could be just as exciting.
Why? First off, the UFC doesn't necessarily abide by conventional rankings. Lyoto Machida was 1-2 in his previous three fights before fighting Jon Jones. Rampage Jackson got his shot after losing to Rashad Evans two fights before. Timing and name recognition means almost as much.
If Diego Sanchez beats Ellenberger he will be on a three fight win-streak with Ws over Paulo Thiago, Martin Kampmann, and Ellenberger. Its not the worst winning streak in the world, he's a big name, and the fact that him and Condit trained together would make things very interesting. Sanchez always comes to fight (except against Hathaway) and is a name that can sell. Ellenberger is an up-and-coming fighter who knocked out Jake Shields and fought Condit before (to a split decision) and that story writes itself. The UFC has also had interim champions defend their interim titles before (Nog vs. Mir I).
None of these guys are the "real" champion anyways because none of them have beat GSP. So why not, while the champ fully recovers, we have a couple of young studs fighting each other?