If there were any people in the room that DIDN'T want Ben dead, then everyone who did want him dead (like Juliette possibly) would have to act like they were freaking out when Jack threatened to kill him.

I believe Juliette was for real when she wrote those notes to Jack. I can understand the 'good cop/bad cop' theory, except that it seriously puts Ben's life in danger. Maybe they figure Jack's not capable of killing someone in cold blood like that . . . I don't know . . . but that's a hell of a risk for Ben to take if he and Juliette set Jack up for this together.