The mistake wasn’t the shot. The mistake was… the dude was able to safely got out and away, and he took an opportunity while doing so to stop, turn around, pull a gun, and shoot.

If you can get away, you do.

I guess the exception would be a stand your ground state. Generally, if someone presents a threat to you or your family, you have no duty to retreat. Fuck around and find out sort of thing.

I wish we could hear the audio, though. Was he an ongoing threat? Was the guy threatening to pursue with more damage? That may change the situation a little. He was a threat in that case, and it should be understood that if you are a threat to someone with a means to defend themself, they will.