I'm not sure. When women chant "Woman Power" - is that Sexism?So when blacks chant "black power" is that racist?
When a group that has and is still being victimized comes together to call for for justice - how are they supposed to express solidarity? "Please don't hurt me any more!" That's not exactly a very strong rallying cry.
If people in Boston chant "Red Sox" - does that make them anti-Yankee (Well, maybe that!)
So, on consideration, I DON'T think chanting "Black Power" is racist in the same way that a bunch of cracker brained white hooded idiots chanting "White Power" would be. Everything needs to be considered in context.