Did you read any of the comments on youtube? The guy was defending his girlfriend from the man. The old man should have minded his own business..I'm sure if you found someone yelling at your spouse and children, having a civilized conversation and respectfully disagreeing with him would be the last thing on your mind.
The YouTube comments seem like a credible source of information.
So you agree with the guy tackling the old dude to the ground but you don't agree with a scared old man then defending himself?
The old man should have minded his own business, no question. But a 28 year old man should have been able to recognize if the old man was an actual threat to his family or if he was just a cantankerous old man.
In the case of an actual threat the driver should have moved away or the husband should have had them move and not left them alone.
Even if the old man had appeared after the guy went in the store and the father came out and saw him standing yelling outside the car if he really thought he was a threat he wouldn't have stop with pushing him to the ground, he would have made sure he didn't get his gun out.
He reacted emotionally and sadly it cost him his life, regardless of the shooter going to jail.