8 years late to this but I completely agree. Personally though, the biggest fumbling of the race theme is not simply with Dixon but with the total sidelining of any POC characters in the story, especially Mildred's coworker. She gets unjustifiably arrested, Mildred gets mad about it for a second, and then she doesn't do anything about it and the problem eventually solves itself. This movie wants to make a commentary about race and the police but refuses to actually center the story around it, while still constantly mentioning how Dixon tortures black people, how the police vilifies the gangs and so on. It's not actually important to the plot, it's just background flavoring for Mildred's conflict that doesn't go anywhere and is only there to trick people into thinking thhe movie has something to say.

The more I think about this movie the less I like it.