1. I'm not the creator of ActivityPub. It's a group effort, by the W3C Social Web Working Group, with leadership by Christine Lemmer-Webber and Jessica Tallon as editors.
2. I don't remember calling everyone on X evil, but I do think using your social media presence to support such an unfair employer is a bad thing to do. If you have some context, I'd be happy to answer to it.
3. I don't know anything about the API at Threads. But it's their API, so their rules, I guess?