So let me get this straight - dude A pulls into a restaurant parking spot and hits dude B's car, the two get into an argument, dude A puts dude B into a headlock, dude A is struck with a metal container by dude B's girlfriend, then dude A is shot by dude B. The family of dude A is suing the restaurant owner because they didn't hire guards that presumably would've stopped the fight.
Full sympathies for the families involved because a lot of lives were ruined, but both dudes sound like jackasses. Nobody is at fault except for dude A for throwing the first punch and dude B for illegally carrying. The restaurant owners had nothing to do with this. This feels more like a cheap money grab by a grieving family than anything else.
Honestly, if dude A attacked dude B without being physically provoked, I don't see how dude B is at fault. Everyone who carries should deescalate or leave instead of arguing/fighting, but arguing with someone shouldn't strip you of your right to self defense if the other person escalates and starts physically harming you. I get I wasn't there and don't have all the details, but it looks like dude B barely passed the legal threshold for self defense, ignoring that he was carrying illegally.