Perhaps they don't really believe Michael Brown was an innocent. Maybe what they are looking for is the right to maim and kill non-blacks with impunity. Given the way Holder is looking at the disparate impact of various laws on the black population (i.e. roughly half of the prison population is black vs 12% of the nation's population), the time may be ripe for decriminalizing various offenses or reducing prison sentences if those offenses are committed by blacks.
The rioting was mainly from outside. The residents likely knew this guy was a big powerful bullie that had abused them more than anyone else. Black on black is easier to get away with which their “friends” in the MSM seem to ignore.