Darwyn Cooke prooved you wrong, dude. One, the idea of ebony wasn't racist. The way he was drawn was racist as hell, but the character in and of himself wasn't. Actually, having a black character of that magnitude in the depression era was progressive. Besides, when he looks differently, he's really useful for the Spirit. The hero having somebody to talk to/confide in/explain plans to is an incredibly useful plot device. They wouldn't even have to give him an origin. The audience sees a black kid driving a cab, they get the idea pretty quickly.
I also loved the way Cooke wrote him. He was like a really level-headed, down-to-earth version of Short-Round from Temple of Doom. He bounced off Denny so well.
Well, considering that we're discussing a character named EBONY WHITE, I think that there was little bit more than the way he was drawn that was racist. Good for Darwyn Cooke for depicting the character differently and maybe even good for Eisner for writing him as a hero, but I think that the name and the appearance of the character are enough to argue that initially, the character was intended (at least somewhat) to poke fun at African Americans.