I don’t know, this seems like something to be taken with a grain of salt. Throughout, the post is dripping with personal contempt for the people he’s talking about. It just seems like he’s taking his personal experience with the “blueskyists” pre Bluesky and turning it into something important enough to coin this term “Blueskyism”, without ever making the case that that’s true.
It’s less, “this is an important thing to consider in contemporary, online political discourse”, and more, “I have personal experience with these sorts of people, and let me tell you, they annoy the living piss out of me.” And I have no trouble believing him.