I don't think most non-white queer folk would have to look particularly hard in their own lives to find racism and erasure within queer communities. Same as the rest of society, really.
Whether or not it's worthwhile to comment on the inclusiveness of queer communities and queer activism by riffing on the inclusive sentiment of the rainbow flag is a different question and one that's really for the people doing the riffing to decide. But yeah, it really ain't fair to equivalise non-white queer folks' experiences of and reaction to racism with people getting upset about a flag.