@touk@dads.cool One thing I found out and seems to be true for my testing on one instance is that if they block them they counter block you. So go into it knowing it is probably not a reversible decision, though I can't see wanting to reverse it.
Personally I see it as part of the EEE plan, they want to divide the fediverse into instances reliably OK with Threads and those not now, in the hope that then people who want to talk to Threads will favour those instances or better yet Threads. A deliberate effort to create a schism.