I seriously think people are wanting to be a little too color blind here. Look, again, I'm a white male and there's things I will never champion myself, women's rights and minority rights. Not because I'm too ignorant to know that they're issues that need fighting, not because I don't think I should but because it literally can't be me. It can't. My group's the reason those issues exist in the first place. Therefore, in those two instances I believe the right place for a white male is standing beside or behind minorities and women in their respective fights not in front. These issues are, boiled down to their ugly but undeniable truths, against the white, male establishment and to ask people to line up behind the very same people is just a little silly.
Some of these counter examples are silly, you can hold a free Tibet rally in the US because how many Tibetan monks are in your city? It's across the damn ocean. But if you fly over to Tibet and start some protest without consulting them, yes that's a little freaking silly.
Again, I think ethically there's no problem, but psychologically I think there's an issue with a white man asking minorities to stand behind them and demand equal treatment from what's essentially the white man to begin with. It's my personal opinion that white people who genuinely want to make a difference should recognize exactly whose movements these really are be happy fighting for equal rights under them as opposed to demanding they fight for their equal rights under him(which frankly is the problem isn't it?).
I hope that's not too controversial that's just how I feel about these types of matters.