It's an interesting situation, defederating.

Defederated instances can see the instance that cut them off and can comment, but they (beehaw in this case) won't see their comments. However, if they refederate later when better mod tools exist, all the comments will (be able to) flood in, right?

If so, they'll need to be able to handle it in some way that enables them to maintain compatibility with their instance ethos.