I think it's important to distinguish between facts and allegations. That somebody, probably Brown, assaulted the store clerk is a fact. The video proves it.
That Brown resisted arrest and assaulted officers is at this point only an allegation. Quite possibly true, but not really proven yet.
Well that we have seen yet but I tend to think that Michele was the cause of his own demise. He'd already been in a row with the clerk...and it wasn't that much time later before the incident where he was shot. His Adrenalin didn't have time to normalize much.