You're right in that #ThisIsNotUs refers to America as a whole, but I still feel like it has the same sentiment as #NotAllMen. People are using it to shift the blame from themselves and act like they had nothing to do with contributing to that culture, which is exactly how #NotAllMen is used. And personally I've only seen white people using that hashtag, probably because most people of color know that it IS us. But I think we're on the same page, other than that!