You missed my point. Yes, you can argue "A rule got broken, so I banned him." But that way you ban for the sake of enforcing rules and not for the sake of the players. A random dude shouldn't get to claim issues with something between two other players. I don't think the way you handled the sit was good either, you !brought me, asked me why I killed him, got an answer you can ban me over, stopped listening and !returned me.
Main reason for this appeal is to get the reason behind the ban reviewed. Maybe policy gets changed or not, either way, I tried.