If I were to guess at the thought process of whoever coined the term, whereas socialism is about redistribution of wealth (tax the rich), cultural socialism is about redistribution of social power (give preference to minority viewpoints).

I didn't name it, and I don't love that conservatives chose language that uses socialism as a boogieman. But I don't know a liberal name for this phenomenon, because liberals don't seem to be doing meta-analysis of liberal culture enough to see the phenomenon in the first place. If you have a better term to use I'll use it, but as it describes a real phenomenon I don't have a problem using the term. Again, I don't believe in linguistic prescriptivism, so I'm not bogged down by terminology, and I don't believe there are bad words or phrases to use when discussing something.