I think most whites will see it for what it is: Identity politics. Race trumping values.
Personally, I think this is a nothingburger for Obama. And maybe a shoring up of the (white) base for McCain. As two can play this game.
There are probably some voters it will help with, but I think you may be right. When Thomas Sowell and Walter Williams appear to be the only black men in the country left to vote for McCain it may raise the question in the back of other voters’ minds if blacks are so monolithically united and motivated on color—can Obama be otherwise?