Are we going to block Meta's Threads.net? I get it if people want to keep things open. However, Meta is a proven bad actor. They claim they didn't put in ActivityPub because it was too complicated to get it done at launch, and they can't get EU approval of their service because of the rampant and invasive data they gather. IMHO, they are going to attempt to muscle the fediverse out of the equation.
Embrace, extend, extinguish. Something that has been used by large companies in the past to push out the smaller, more open systems many times.
That said, I agree with @Dsaf@midwest.social that blocking by default would be against the open platform that we claim we want. Users can choose to block accounts themselves or not interact with Threads. So long as these instances are publicly available, there's nothing stopping big companies from hovering up the data passing through them whether or not they are attached as a peer.
Those are the two main points that I've seen as possible concerns with allow federation with Meta or any other commercial property and neither is really that severe.
The good side is that, for folks who are only ever going to go with a big company's site, it still allows us more privacy-minded folks the chance to interact with them. Something that is just flat out impossible today without compromising our own principles.
to me, this is very reminiscent of the paradox of tolerance. just because we want an open platform doesn't mean we need to, or should, support those who do not have that same thing in mind.