I applaud your efforts, fairbanks. I know it's tough to debate this kind of thing, but to make a good argument, you must know the subject you are arguing about, and like others have said, I think you are missing a piece.
Science never claims to get anything right on the first try. So, these racist ideas may initially be created by people claiming science, but where real science comes in is when these ideas are disproved. Science is humanity's best attempt at objectivity, but people's will is a powerful thing to fight. It creates bias.
So when Snozz said "exactly", it was because you proved his point.
The more science has uncovered about the human genome, the more the idea of race disappears. Race isn't even distinguishable from a scientific standpoint. It truly is skin-deep, and barely at that.
Just like crooked preachers can warp the truth of the Bible (there are truths in there, but not The Truth), so too can people warp the truth of science. It's only a tool.
Edit:
Just thought of this. I think your aim is slightly off. Your arguments are sound, but in this case, your beef lies not with science. What you've shown is the pitfalls of how people can take anything and manipulate it to suit their desires. Science has shown us that anyone claiming evidence to support racist views should be regarded with suspicion.