Lacey is interesting, he says the resentment theory is nothing that's going around at the site. The men he attacked weren't even his superiors. Not a chain of command problem. He said it was about his religious beliefs.
Well, when you've got a Muslim attacking US military personnel, you have to figure that his beliefs are a pretty likely place to start the search for motive.
I mean, if it had been the local translators they originally suspected, surely they would not have ignored the fact that they're Muslims.