yeah, the fact that he was black I'm betting had a lot to do with any escalation of the situation
Yes, I do. Several of the major African countries have a very demonstrative, rough-and-tumble culture -- much like China. The kind where you have to assert yourself in order to avoid being walked on all the time. But he was black, and the Chinese were predisposed to be distrustful and fearful of him. (Kind of that "One false move and I'll ..." attitude.) So I imagine he did something that they perceived as aggressive, and they went into a frenzy.