I forgot about the Arabs as well who usually aren't black and definitely not indigenous. I wonder if those three groups feel insulted by the BIPOC term.
This is more of a pondering and I think the reason BIPOC is so annoying is that certain races are given top billing (just like the new pride flag) while the others are treated as an afterthought. (See Asians and Hispanics)
The problem is that your feelings be damned, but biological men and women (in general) are built different. So you can claim to be a bigender non-binary, but t-shirt makers would have a hard time building a general shirt for you.