Seriously, you are hating on a law without even understanding it.
All of the US has pretty much the same self-defense law, if you have a reasonable belief that your life is in imminent danger, you can use deadly force.
Where the differences come in is if you have a duty to try and retreat prior to doing so. Many States say that if you are in your home or vehicle, then you don't, in other places you do. Florida says if you are legally in the place, then you don't have retreat. This is the only difference, and that is what SYG is, period, you don't have to retreat from someone threatening you.
And it's irrelevant in this case anyway.
The guy was on the ground, and thus he couldn't retreat.
Even if he was in NYC which requires a duty to attempt to retreat if you can, that he was on the ground negates it because he couldn't retreat.
SYG is thus totally irrelevant to the entire thing, and it's simply a case of did he have a reasonable belief that his life was in imminent danger.
The video would suggest that the answer to this is no, that any such fear was unreasonable.
The Cops have the Law wrong. The Sheriff stated that we couldn't put our belief over the shooters, but in fact that is exactly what the Law demands. It demands that the fear is reasonable, in other words, if a reasonable person was in the position, would they consider their life to be in imminent danger.
As I said the answer is no. Thus he should be charged with Murder 2 and plead his case in court. Simple.
The Sheriff has it wrong, so stop beating on a law you clearly don't understand and place the blame for the failure to arrest where it belongs, squarely in the shoulders of a dumb-ass sheriff who doesn't understand the law he supposed to be enforcing.
And yes, the media don't understand it either, well they might, but they like to use flashy headlines and stories to sell their news so it's easy to paste SYG everywhere and watch all the half-educated explode as they respond to the click-bait.