Since Threads requires signed fetches, and you can easily circumvent blocks of it by switching to a new domain, it suggests they will move to a domain reputation system in the future where new domains need to become established in the network, similar to email, before federation is allowed. They are operating on a blacklist for now but it will slowly become more whitelistly as people push back.
Discussion
What I mean by "you can easily circumvent it": you can stay on the server that you're on, but run a separate service on a different domain to sign fetches for you, and then transfer the response to your main site. You can do this infinitely to keep circumventing it until they switch to a reputation system. It's inevitable. The question is whether or not we should speed up that process.
😥 zucked again