Transitive defederation -- defederating from instances that federate with Threads as well as defederating from Threads -- isn't likely to be an all-or-nothing thing in the free fediverses. Tradeoffs are different for different people and instances. This is one of the strengths of the fediverse, so however much transitive defederation there winds up being, I see it as overall as a positive thing -- although also messy and complicated.
The recommendation here is for instances to consider #TransitiveDefederation: discuss, and decide what to do. I've also got some thoughts on how to have the discussion -- and the strategic aspects.
I can understand defederating from Threads, but transitive defederation is bordering on insanity.
This will do nothing but exert peer pressure onto instances that wish to remain impartial. Transitive defederation will play right into Meta's hands by fragmenting the Fediverse further.