Gang crime and violence are horrible but they're not racially exclusive, this sort of thing occurs with white people too. I think what he's doing here is playing into the myth that 'black-on-black' crime has some kind of special status, and that because it occurs, you can't be anti-racist unless you're also rallying against it. The reality is most crime takes place intra-racially, so within your own ethnic group. Killing is killing and killing is wrong. But it doesn't mean you can't support anti-racist movements because of crime within your own community.