I respect the hell out of you, major, but I definitely disagree on the facts. I absolutely agree that there was no legal right for the man to shove the guy to the ground. Nothing he did gave him legal justification to assault him. However, the assault ended and so too did the reasonableness of the shooter to have felt he was in immediate fear for his life. That was done when the man backed off. It would have been a closer case had the man drawn and fired DURING the shoving assault, but that's not what happened.
Sorry, I still disagree. The power and impact by which the shooter hit the ground is enough for him to be in fear of his life. There isn't time to ascertain whether the threat is lethal or not, he was in fear for his life and took appropriate action to defend himself. Monday-morning quarterbacking--as everyone on this forum has the luxury of doing--is one thing, but all his lawyer has to do is presenting the victim's state of mind after being so badly assaulted which will be enough to acquit him!
Simply put, and as has been stated before, put a police officer in the shooter's situation. Do you honestly think an officer wouldn't have reacted the same way?