What possible reason could there be to keep David around?
He should have been the first to go just for his paranoia alone. The guy also sucks at challenges. Possesses no social game. He may be a number for a few minutes then he gets paranoid and defects. It will be the Alpha-Males downfall that they did not get rid of this guy. He will be the perfect person to recruit for an opposing alliance.
He's now even got the Immunity Idol.
Just stupid to not get rid of him first.
...............ZING!