Go in any French communist cafe and the word communist or progressist is completely interchangeable. This author is progressist, ie. he adheres in their views to the goals of the advanced thinking of communism. It is a term meant to differentiate the communist from the traditionalist who are called names such as “neanderthals” etc...
Actually, I think the preferred term was “reactionary.” In the Soviet Union, that word could get you arrested...
That is why I used to have a tag line like “I’m reactionary, hirsute, gun-owning, knuckle dragging, pro-life, Neanderthal and proud of it!”
I’ll probably switch back to after the election.