The idea is that if something negatively affects protected group(s) disproportionately, then it doesn't matter whether the mechanism by which it does so is via class -> strong race/class correlation. It's still discriminatory.
I'm a white male but I know that personally I had no clue what Crew was during my high school years. Anecdotally, I went to school in an area where the public school population majority was, well, what we consider the minority when discussing race relations.