At this point, I don’t think he could step in. There’s too much evidence that Brown assaulted and charged at the cop. Zer0’s normal MO is to declare one side (usually the victim) the “winner” absent any fact (c.f. “[The police] acted stupidly” in the Cambridge incident).
Here, there’s plenty of public evidence that the cop in fact acted in defense of his own life, against a known violent criminal. Since Zer0 and the JustUs department are not about to start criticizing their “own people”, they’re going to stay out of this one.
I think he did declare a side by sending in the Holder strike force. With zero evidence of a cover up, there is no reason except pandering to send in anyone from the DOJ obviously on a mission to drive the matter to a trial. If that fails, the fall back will be a civil rights charge.
Now, there are forces out there Obama can't manipulate. What's going to happen if they bring their disgusting behavior to neighborhoods and schools with large non-black populations? People are going to defend themselves if the police won't take forceful immediate action against criminals.