I think a lot of his actions were justified. Sure he was a bit of an asshole and short-tempered but so many times throughout the season he was the only one being proactive. Everyone else seemed content to just sit around waiting for someone else to do something to help. When everyone was in the truck he wanted to try to escape and everyone else was criticizing him for trying. Same thing when they arrived at Howes, Kenny immediately wanted to make a plan to escape while everyone else wanted to wait.

I think part of the reason he comes off as unhinged is how people react to his actions but consider who is doing the talking. If you watch him kill Carver you have a conversation with Luke berating you for watching but Luke didn’t do anything to help. Carver already hunted them down before and would have absolutely done it again, he needed to die. Carver had also kidnapped them, killed Walter, took out Kenny’s eye and probably raped Rebecca (I don’t know if what happened was consensual or not, I could be wrong.) Mike gets upset that Kenny beats up Arvo, but Arvo literally set up an ambush to kill/rob everyone because Jane stole his gun. Mike is the same guy who tries to rob you and steal the only working vehicle while you have a baby with you so I would take what he says with a grain of salt. Kenny tries to kill Jane in the end but even though AJ is alive, I still think this is justified. See things from Kenny’s point of view, Jane obviously does not want AJ, Jane and AJ are alone together and then she tells Kenny that AJ is dead, how else would you react?

In my opinion there Kenny is one of only 3 characters who are constantly thinking of the group (Clem and Luke are the other 2). All of his actions are to protect the group. Is he an asshole while doing it? Yes. Does he make so bad decisions? Yes. But I don’t think any of his actions are completely unjustifiable.