Excellent points. I'm not sure why black kids have always been so fascinated with martial arts and 'kung-fu movies', but you're spot-on. A man like that could certainly attract an audience and captivate some young minds.
What I'm driving at is that you might do better to make your initial appeals to adults rather than at risk youth. If you frame your pitch well and don't ask for anything that's going to put them off in early stages, I'd think you'd get a lot of interest. If I were doing this, I'd tell local business owners that 'we' are just looking for positive role models for at risk youth, and would they be willing to display this sticker in their shop window or on their company vehicle like their neighbors will be doing. If they press for an answer on what they're going to have to do, I'd say they might be asked to give a short talk sometime but only at their convenience. The main thing in the early stages is getting them on board. Later on, you can ask for progressively more and more from these people (give this kid a job, let these kids use your gym, teach these kids judo, act as a mentor to this kid, etc) bearing in mind that their willingness to accommodate your requests will be proportional to their perception of the strength and utility of your movement.
Getting youth on board is another matter. You can't expect them to turn up every week for an hour lecture on the virtues of education down at the corner butcher shop. They simply won't turn up. Something 'cool' like martial arts will keep them coming back and have them feeling like they are associated with an organization with some balls to it. Not sure how much you know about the birth of the Black Panther movement, but when people feel beat down or under threat, learning 12 ways to break people's arms tends to hold their attention. Again, the main challenge is just getting them on board and establishing a group mentality. When that's done, you can begin to introduce other aspects and preaching about things which would have sent them running for the exit on day 1, or organize protests to address issues that are on the local mind.
If things go well for a few months, you could contact black celebs to see who is willing to make appearances, see if a local accountant would be willing to get you registered as a charity on a pro bono basis and start asking people/firms for money, see if legal firms would offer pro bono help, and establish a chain of command that would let you begin to branch out to other cities using what you've learned.
Those are my initial thoughts anyway on how to establish the identity of your organization. Too spooky? What's your plan then? Come on, spill it.
