Do you honestly think that will make the slightest bit of difference to a racist? If so, maybe you should join the rest of us in this world, and actually talk to one.
The technicalities of race are completely, totally, thoroughly, and in all other ways irrelevant to the issue. All that is important is perception. It doesn't matter what you call the difference -- race, ethnicity, genetic markers, etc. -- all that matters is the perception of difference, and the judgement of "difference == bad". The beligerent pedantry you get off on is simply teaching a pig to sing. Bigots won't accept that there is no significant difference, because they can see and hear the difference. Whether they can exhaustively describe said differences in a matter acceptable to you doesn't make any difference at all in the real world, and claiming it does is ignorance and hubris.
Humans are not rational animals, they are rationlizing animals. The only thing that is going to change the subject is not nit-picking technical debates on the nature and validity of the perception of difference, it is changing the "difference == bad" judgement. Accepting difference is what is important.