It's bad to treat smart people like they're dumb.

This will happen anyway, in fact it will happen more often if relevant information is discarded. The difference is that the victims will no longer be correlated with race. Thus we are still left with the question of why adding race makes it worse.

Edit: Another way to express what I'm trying to say is that your argument, if it works, shows we should avoid using any data that's correlated but not perfectly correlated with intelligence, e.g., test scores, grades, job performance, pretty much anything really.