Kenny is an asshole. He wanted you to drop Ben to his death.
Just because I don't agree with Kenny 100% he sometimes will choose not to assist you when you really need it.
I hate Ben and think a lot of his decisions put my group at risk, but that is not enough motive to just feed him to the zombies. He still deserves better than that. I want him to die because he fails himself, not because I just decided to kill him.