My character would have killed this guy back on Gomorrah, but I recruited him because there are two steam achievements associated with having him that I wanted. Then, you can get those achievements immediately, but I forgot and he stood around for a while, long enough to trigger his companion questline. So at that point, I decided to just keep him around for the sake of muh content and seeing what the quest had.

Heresy is a slippery slope. I was supposed to kill him but i didn't, and now he's still alive at the end of the game. I'll be sure to kill him right before the game ends. When is the latest you can kill him? I'll finish his quest and see everything and then kill him at the last moment.