Had he and his administration kept their mouths shut and not commented about it, there wouldn't be riots and people's businesses and jobs being destroyed in Ferguson.
According to who? You seem rather certain in your alternative hypothetical time line. What makes you believe you have any idea what you're talking about?
He does this every single time there is a crime involving a black person. Although throughout his administration, he has made it his mission to pit American against American, it seems stoking the flames of racial division is his personal favorite.
he does this when there's a crime of national note. No black people died in the Newtown shootings. Yet Obama spoke on those crimes as well. Obama spoke on CIA torture, despite the fact that it didn't involve a black person specifically. Obama spoke of former Marine Andrew Tahmooressi despite Andrew Tahmooressi not being black.
Race is not the common denominator. National relevance is. And often racially charged cases are of national relevance.