I proactively blocked the box of c*nts, aka Facebook’s new Threads domain, on the user level. It’s not easy, but here is a link showing how to do it. https://medium.com/@geofbard/how-to-block-server-domains-in-mastodon-899b24f8fb6e
We’ll see if it works once they add Activity Pub integration.
And I blocked them because they are a box of c*unts. And I’ll leave it up to instances to do whatever they want with Threads.
I’m sure there will be some instances which will federate with Threads. :(