FWIW, in the context of the larger protests, the exact details of the shooting do and don't matter. Most folks didn't get out there because Michael Brown was killed. They got out there because Michael Brown's death felt like a straw that broke the camel's back.
History is littered with cases in which the characters in the event that proved the tipping point weren't ideal (especially in cases revolving around civil liberties). But I think it is important that we recognize that what is going on is about a lot of things on a lot of levels. We (as in: all of us trying to engage this on a constructive level) must not excuse problematic blemishes in one side of the argument to dismiss problematic blemishes on our own side of the argument. One thing that seems pretty clear is that in any human endeavor this complicated, there are flaws and blemishes all over the place.
I say this to point out that this seems to be one of those points where well intentioned individuals from both sides (I hesitate to even put it into a simple binary) can sit there and talk right past each other, each growing more and more frustrated that the other doesn't get it. I'll point to the 7 Habits of Highly Effective People: "First seek to understand, then to be understood."