It isn't specifically limited to those specific narrow words by the most limited means you're thinking. I'm sure they could make that argument, but only a fool would risk a discrimination lawsuit based on hair color. Even if that is the specific reason a person would have to be either a fool or want to try to challenge the law, and there is no guarantee after losing that the Supreme Court would even take the case. I don't think the Supreme Court would even want to touch such a case nor that it would be ruled on in the manner you're thinking.