Self-defense against an unjust aggressor is justified.
Arguably, even against a just agressor self-defense is justified. The ancient Israelites invaded Canaan and were told to leave nothing living. G-d told them to do this from on high. Were the ancient Canaanites to just lie down and bare their necks? No. They fought back ferociously.
Likewise, the American Indians—sorry. Native Americans—retaliated viciously for the US cavalry’s campaigns against them, and also massacred settlers who had done them no direct harm. There was justice to their violence, and it was in some degree self defense. But did that mean that the settlers and the cavalry had to just lie down and take it? Of course not.
In a bare-knuckled war, violence is justified on both sides. That doesn’t justify Nazis sending innocent non-combatants to the gas chambers, or wiping out whole villages to get rid of partisan fighters. But it does justify firing back when someone fires on them, regardless of who’s right and who’s wrong in the substance of the dispute.
Gooeyfart has been breathing in his own flatulence for too long. It’s effected his judgement.