You cant kill Gale.
You can leave him to his doom when you first meet him. But thats the last chance you get to kill him.
I mean OK, you can get him to -50 approval, attack the grove, etc. So you can get rid of him.
Cant kill him, though.
You can also tell him to leave after he reveals his "condition" right ? I never chose that option, but I assumed that he would leave if you told him to.
