He had retreated though, since he wasn't shot at close range. He wasn't close enough to actually reach for the gun again, so clearly he had backed up. Certainly it wasn't shooting him in the back as he ran away like this South Carolina case, but the argument that Brown was actively a lethal threat because he had previously gone for the gun isn't convincing to me.
My memory is foggy, but I believe Wilson claimed he shot Brown while he was charging back toward him. Based on the previous scuffle over the gun, Brown charging him again could certainly be considered a lethal threat.
With regard to this recent shooting, even if the guy had actually stolen the taser it would be very hard to justify those last couple shots. It's also easy for me to say that, and maybe not so easy for someone under a tremendous amount of stress to calculate the risk someone poses, or to even see if the taser was in his possession as he was fleeing.
As far as the black community versus the police, it's a situation where both problems fuel the other in an ongoing cycle that's never going to end. The portion of cops that are on a power trip give cover to the crime problem in the black community because shootings like this will yet again be touted as the norm, not the exception. It will give the left another opportunity to victimize an entire class of people and convince them that they aren't responsible for making changes within their own community (while of course pitting all whites against all blacks in the process).