Hrm, I’d have said that Mastodon, if anything, was leftier than bsky (unless you count Trump’s mastodon instance, but as it doesn’t federate you probably shouldn’t). It would certainly have a larger hard-left representation. Nostr, being vaguely crypto-flavoured, is messier.

Given that Twitter has been taken over by a far-right lunatic, one might reasonably expect the alternatives to lean a bit left.

The left-leaning vibe is a historical accident reinforced by user-managed moderation.

Bluesky came at the right moment to pick up lots of people fleeing Twitter after Musk's overbearing edgelord enshittification of Twitter.

Now, Bluesky's robust moderation tools allow users to subscribe to user-curated block lists. Users are empowered to decide they don't want to hear certain viewpoints. You don't want to see cat videos? Subscribe to a block list.

Right wing folks mostly don't care to try Bluesky because they have Twitter, but those that do try don't get much traction because no one sees their posts. Trolling and rage-baiting become unsatisfying when you're talking to yourself.