Wrong. Legally.
At the time her husband appears the shooter was three feet from her and arguing over the HC parking spot. While one can say that's being overbearing, it's not illegal, and the old guy was right about the illegal parking in a HC spot. He could have taken a photo of the car in the spot and called the cops to wtite a ticket for a ... what $ ....
OK..I looked it up for Tennessee. Evidently, so many folk don't take it seriously that in 2008 ...
What it comes down to is the young ABLE BODIED husband disrespected any HC person who might drive up and need that that spot. When he violently pushed the old guy down, he performed the illegal provocation.
You might say he pushed him down instead of hitting him with a closed fist, but the number two killer of seniors is the consequences of a fall. Brittle joint bones break. Hitting with a closed fist could kill many seniors with medical conditions for which a HC parking permit could be issued.
If the husband had kept his head and talked it through he'd be alive.
The shooter should not have completely unlimbered his weapon. There's the real crux of the issue. And he had the opportunity to not pull the trigger.