Most witnesses say he was advancing. The "new" ones add Wilson was retreating while firing. As K_Z so aptly pointed out, those two elements were not happening in a vacuum. Per my previous post regarding Wilson and corroborating witnesses, the officer did hear the BOLO before getting attacked by Michael, then Michael knocks him back into the SUV, pummeling him, struggling for the gun, does not stop his attack despite two warnings the officer will shoot, only stops once the officer fires, and then advances on the officer again, ignoring an order to freeze just like he ignored the lawful order to get off the street. Nothing about this looks unjustified to me.