A couple of things. This didn't happen in slow motion for Drejka to watch unfold. I'm sure that he was startled and scared.
 Also, another man was coming out of the store right after McGlockton. Of course, he got out of the way, but Drejka didn't have but a second to determine whether or not that guy was an accomplice or whether McG was backing away to pull a pistol out. He reacted very quickly to insure his safety. Maybe he shouldn't have after looking at the tape, but he didn't have that luxury.
		
		
	 
This is what hasn't been answered. The shover instinctively turned his right side away (present a smaller target) and put his hand to hip/pocket height. Shovee couldn't see whether he was reaching or what for.
I've asked this twice and marcus once... If a police officer shot someone with this video as evidence, and a police officer defended his decision with, "I had just been violently shoved to the ground on a blind side. One guy was posturing over me and closing distance. Another was on his way over as well. I drew my gun and the closest aggressor backed up two steps, turned his right side away from my purview, and appeared to be reaching for a gun. Out of fear for my life/safety, I fired one shot."
I imagine a lot of people in here who are saying this guy should do time would be defending the officer.'s decision And I seriously can't understand why. We give police officers, who are paid to protect us, and who have been given hours and hours of training at our expense, more leeway on fear response and decision making than we do average citizens who are physically assaulted?
I'm not defending the shooter. He sounds like an a-hole who should have been arrested a couple of times over. He sounds like a busy-body that should stay out of other peoples' business.
But--again--busy-body isn't illegal. Needing to be arrested in the past doesn't call for a make-up arrest now. Being an a-hole isn't illegal, or all of you guys would be locked away forever. 
 
The guy was assaulted from out of nowhere. He was laying prone and helpless before a guy that was closing in. His fear response kicked in. "Backing away" or not, I don't see this as immune from SYG defense.
It's sad. It's needless. Yet it's also probably quite Darwinian... 
Maybe we should put a new gun law on the books... Stand Your Ground laws in all 50 states. Caveat is that every person in the state gets a text message every morning reminding them to be polite and not to assault someone because there is a SYG law in effect and you may get a toe tag for being a tough guy.