The only reason Rick is alive is because the show’s creators wanted him alive.
Well that’s understandable from their perspective. Still, it’s a bit unrealistic, and there’s no reason for Negan to keep him around, unless his sadistic need to show he is the boss and has the power to break the leader outweighs his intelligence. This episode didn’t really show the reason for actions that are contrary to common sense. Why does Negan even want Rick alive and around?