You see how he tried to scare them at first? I can only assume he thought they would be reasonable and back down. Once he realized he was going to get arrested while the neighbours point and laugh, life ruined, never own guns again, extreme humiliation and forced to live next to these scum unarmed... That's when he shot the guy. "pussy huh?" I could only imagine how good that felt. But like you said, why not beat them up? I would have just stomped them to death after the handgun was empty. But that's me. This guy probably wasn't confident fighting.