This is new. I never heard this rule for 'african-american' before.
It doesn't sound like a rule for African American to me; it sounds like a rule of biology, honesty, and decency. My son is biracial, and if you referred to him as if he weren't half white (i.e., as if I weren't his father), I'd knock you on your a$$.
But I don't think 'half white' and 'african-american' are mutually exclusive.
That's something my father would say, and he'd actually do it too. Anyway, Barack Obama knows where the money is and right now it's in race hustling (no one can beat Jesse Jackson for that though). Aside from that, his platform on issues is disgusting but because of the mess that is the republican party he'll be elected.