Why are White on Black bias attacks treated differently than Black on White bias attack?

I doubt that anyone in America does not know about the Trayvon Martin and George Zimmerman case. The black community was up in arms over what appeared to be a case of racial profiling and, sadly, the homicide of a young black man at the hands of a white man. Truth be told, many white communities supported the black community in condemning racial profiling. Personally, I was shocked when George Zimmerman was found innocent on all charges. There was astounding amount of media coverage over this case. But, what I found peculiar was that there are several examples of Black on White bias attacks which go largely unnoticed. For example, on September 4th, a black man in Union Square Park, in New York City, shouted, "I am going to punch the first white man I see." And, he did just that. Lashawn Marten punched a 62 year old man, Jeffrey Babbitt, so hard that he was knocked out and his head hit the pavement. Two men came to his assistance and Marten attacked them. When the police arrived, he challenged them to arrest him. Jeffrey Babbitt was rushed to the hospital and was found to be in a coma. The doctors announced that he was brain dead and unlikely to recover. A few days later, Babbitt died. Lashawn Marten denied it was a bias attack and refused to accept that he was responsible for Babbitt's death. He demanded to see Babbitt's death certificate. Strangely, the black community wasn't up in arms over this obvious bias attack. Why not? I would think the black community would want to show that Marten's actions and beliefs do not represent those of the black community as a whole.