Nothing ridiculous about it that I can see. Isn't the practice of favouring publicly funded projects in places where they will help win votes and protect candidates from defeat (and vice versa) quite common in the USA? Isn't there even a term "pork-barrelling" that's been coined for it?

Discriminating in practice against black Americans - for example downgrading public projects especially affecting them (such as maintainance and improvement of the New Orleans levees) wouldn't have to be done on the basis that they were black. Doing it on a basis of voting records and expectations would have exactly the same effect. And very few black Americans were likely to vote for Bush, even before New Orleans was washed away. (Nobody will ever have a chance to do so ever again now, of course.)