I guess what I am saying is that there are people who will say "I (or my child) am/is biracial, I am NOT BLACK. I don't look Black, I don't fit in in the Black community, it doesn't accept me."
I agree - if you are biracial, then that includes the Black parent.... so why is it a problem to say you are Black or for someone else to say you are? You ARE... and you are also white, or Asian, or whatever other ancestry you have. And you can also say you are those things. However, unlike Black people, THOSE groups are unlikely to accept you as belonging to them unless you offer a qualifier. You can still try but likely won't have success.
If you live in Latin America and you are "biracial" but look white, you CAN say you are white and have people accept that. It's all about perspective and where you are.
I don't think that mixed people should be "forced to proclaim their Blackness over every other culture." I don't believe that's what I said at all. All I said is that, while I respect peoples' rights to self-identification, I don't find the term "biracial" to have much meaning or accuracy as I see it. That is it. If you like the term, use it - no big deal! And I absolutely think people should acknowledge the full spectrum of who they are, but also acknowledge the realities of the society in which they live.
Get used to me. Black, confident, cocky; my name, not yours; my religion, not yours; my goals, my own; get used to me. -Muhammad Ali