What happened was a situation got out of hand.
Wilson got pissed that Brown basically said fuck off and he slammed his brakes and floored it in reverse almost hitting the two men walking.
So close that when he opened the door it bounced off Brown.
He grabs Brown, Brown fights back, Cop panics, shoots Brown.
Brown now wounded, runs, cop keeps shooting at him.
Brown being shot at stops, get hit, stumbles, gets shot some more and ultimately killed by the final bullet.
I don't know if you even charge Wilson for anything for that.
But the narrative that Brown was attacking him was just wrong.