The parent is using the term pejoratively. In this context, I would describe it as calling someone a poseur of liberal/progressive issues, i.e., someone who cares more about the appearance of supporting progressive issues than actually supporting those underlying issues themselves. It means calling someone dishonest about their outward intent, basically. Personally, I'd prefer that people would just say what they mean rather than relying on slang entangled in the modern culture wars.