What do you mean? You mean that racist societies might be expected to distinguish between races with noun classes? Seems to me this might well have happened in some language at some time, or at least a variation on it: distinguishing between those inside the clan, and those outside.
It looks like the sex distinction is the one most commonly reflected in language, which strikes me as empirical evidence that it's generally the most valuable one.
> Common gender divisions include masculine and feminine; masculine, feminine and neuter; or animate and inanimate.