I think you're conflating a couple things here.

Firstly, the notion that Lemmings are xenophobic is false. While there's evidence to support this claim, on closer inspection you'll see the issue isn't about embracing new platforms, but the type of platforms. This attitude goes beyond the Threadiverse and is in fact one of the fundamental attitudes of the fediverse, as exhibited with corporate instances getting fediblocked on mastodon.

To suggest that everyone is petty because they're not embracing corporations is a giant stretch.

Counter to the outright lie that's being peddled here is the excitement about NodeBB and its ActivityPub implementation.

Secondly, people hate Facebook and rightfully so.

Thirdly, BlueSky is still a corporation who, doesn't implement ActivityPub and have built a platform that pretends to give people power while hoarding all the real power for themselves.