Here's my theories, for all their worth.
First off, Thor held back cause he didn't want to hurt the Ultimates, he wanted to make them see the truth.
Secondly, that wasn't Scarlet Witch talking to Quicksilver to make him get back up again, that was Loki in my opinion, pretending to be the witch. He used Quick's love for her to make him do that. If I remember my mythos correctly, Thor could only weild the hammer when he was wearing a belt. If I remember correctly, but I'm sure someone will state if I'm wrong.
Third, Hawkeye could be the mole, but I'm betting it's Loki. Just his style to keep everyone guessing.
Lastly, the crack about Middle Est at the end showed that Thor was correct in the fact The Ultimates are starting to be used for non-superhuman affairs. With the team's conscience gone, Fury can use them as he sees fit.
My two cents.