Well, we agree that the real world isn't pretty when it comes to race. And being in the skin I'm in, I've certainly had my share of demeaning treatment. But, I also know that the people who treated me that way are the ones with the problem, with the small-minds. Yes, I acknowledge that some of them were also in the power position, and that makes for this very major issue. But, things don't change by themselves. So, as a person responsible for teaching a member of the next generation, I will alert her to the dangers of the world, but also constantly remind her that that is not how it should be. That said, my wanting her to identify as biracial (if going for the "short version") is not an attempt to give her distance from being Black. She is Black, but she is also just as much Polish. I could ask why no one wonders why I may not be trying to give her distance from Polish.
My not identifying as biracial if an ancestor 5 generations removed was White seems to buy right into the one drop rule, as far as I'm concerned. In my mind, that would be like saying I am at high risk of cancer, if that same ancestor died of it, when no other had. It would also look suspiciously like what you and others who hold similar opinions think, that they are trying to be NOT Black. So, no, I would not claim biracial if I found my 4th great granddaddy was White. And, yes, I'll admit that I might look sideways at someone who did...Then I'd go on about my business, because that wouldn't be mine anyway.