Guys, if his story is accurate, I don't entirely see how he's being a douche. If he said "hey, do you mind if I leave to go do this with some guildies", and the raid leader did indeed say "yeah, sure, I understand", then why the attacks?
I know there might be more to the story, but let's for the sake of argument and seeming overly critical give him the benefit of the doubt that his story is point on.
If you want to see a "douche" move, try the guy that left my old guild back in BC, then started taking his friends to the Kara ID that he was saved to, that we were trying to go in and finish clearing that evening. THAT was a douche move. The leader refused to leave, knowing full well and good it was a guild run started by us, and then two rogues went and did chess (which, actually I did think was kinda funny), then proceeded to pull mobs onto us while we were waiting for a resolution.
That was a douche move.
In the end, OP, sadly Blizz can't, or in my experience won't, fix the ID. You are stuck until next week. Trust me from personal experience.
To the Prince of Bel Air quote, that was total win.