Racism/sexism/whatever... a wrong is a wrong. Fight it wherever you find it. My example was an interaction between two people, two individuals, and now you're talking about "discussing social groups". Racism and sexism is caused by considering people as "groups" and not individuals, and your solution is to... do more of the same. Recursively. All I have seen the left do in the last 40 years is carve up society into ever smaller and more specific groups with associated victim-hood points and it doesn't get us anywhere. All you are doing is entrenching division.