Just a hunch here, but I don't think the author is being racist. It's a rhetorical device: he goes from "half-black" to "100%" (Marxist).
Now I could be wrong — he may be a racist — but nevertheless it is a rhetorical play on words. And probably ill-advised.
Funny how when 20% of white voters would never vote for a black man, it’s called racism. But when 92% of black vote for a man only due to the color of his skin, even though he is only “half-black,” it’s not racism...
Obama spent 20 years in a church based entirely on racism and nobody sees a racist. This writer points that out and he’s a racist?
Only in Marx logic!