Wiggins didn't actually attack anybody. He just ground everybody into dust like he's Ivan Basso or something. Nibali and Martin had been away attacking. If Pardilla or Seeldraeyers had made it to the finish and took the win I wouldn't mind either, because they did a lot of animating the climb too. No, there weren't people on different teams working together there. Froome did all the work, then Wiggins took over. Wiggins wasn't really working to distance the people behind him; if he'd wanted to do that he'd have been setting an inconsistent pace, dropping back and bolting. No, he'd already distanced everybody he wanted to distance, bar Nibali.
If you watch cycling regularly you'll see quite clearly that, in the case of a group finish, the absolute worst place to be is at the front, because every rider behind can get the jump on you. Very rarely does the guy who leads out take the win. The only notable exception I can think of recently is Evans in Montalcino, who just roared around that final corner and took the last ounce of strength out of Cunego, who was on his wheel hoping to take the stage. Wiggins knew he had to be on the front because it was him who was setting the ferocious pace, and the others knew that he was the strongest, but was no use in a sprint finish - Wiggins is a rubbish sprinter. Wiggins therefore knew that his only way to win the stage would be to drop them all, the likes of Martin and Mollema knew that they could outsprint him, and aimed to do that.
Because Wiggins was out for GC time, he was content to sacrifice not winning the stage for grinding out a bit more time on his rivals; he probably didn't expect 3 of the 4 with him (not counting Froome as Froome obviously wouldn't pass him) to get past him so that he took 0 bonus seconds, but he took that gamble, because that gamble was well worth taking.