Step one is understanding you only control your own thoughts and actions. Step two is learning how to control your anger and use it as fuel for deliberate actions.

Honestly, I think Luigi here just followed this wisdom. Recognised that he was rightfully angry at the system and directed that anger at someone responsible. You only control your actions, and your action can be to shoot a motherfucker on the street ¯\_(ツ)_/¯

I’m not condoning or saying it’s morally acceptable, but I don’t think it’s philosophically incoherent.