I have a theory that Jack might have been a CIA agent or some other kind of spy. I'm basing this mainly on Evil Coop massaging his jaw in the last scene we see with him before we find out that he's dead. Is it possible that Evil Coop knew Jack was some sort of Government agent sent to kill him? Could the massaging of the jaw actually been Evil Coop feeling his teeth to find a false tooth containing a cyanide capsule? There is a distinct crunching sound in that scene at one point, almost like something cracking open.
Thoughts?
Interesting thought! I was thinking it was a show of dominance, but I like your theory.