Ignore it. Defederate. Defederate with any instances that chose to federate with it. Keep the fediverse small and independent. It’s nice here, let’s keep it nice.

I keep asking but haven’t gotten an answer, why must instances that block meta also block those that federate with META? Wouldn’t blocking META be enough, as you wouldn’t see their posta, nor users, nor comments in any way after blovking the domain?

Is this punitive or is yhere a reason I’m mising?

I got the impression that somehow your activity 3rd hand can still be passed on via the intermediary instance to Threads, and then becomes part of their dataset. I could be wrong, I’m not sure how that information gets passed on in the backend.
In a federated system, users on Alice can see and post into communities hosted on Bob, eg alice/c/funplace@bob. When Meta tries to join, Alice chooses not to federate - avoid giving meta free content, protect its users from ‘bad’ meta communities, preemptively block toxic meta users, whatever - but Bob does federate. Alice users can’t see meta/c/advertising, there’s no way to subscribe to Alice/c/advertising@meta. Both Alice and Meta users can see Bob/c/funplace, and so alice users can see anything that meta users post there and meta ‘gets’ any content that alice users contribute. Bob effectively acts like a tunnel between alice and meta users.