Indeed, so it seems reasonable to help a countermovement grow. Defederation makes it quite a bit more complicated for new users to choose an instance and for anyone to switch instance, and goes a bit against the idea of open social media.
And if moderation is not done because it’s a choice to see them and they are barred from posting in one’s communities, the cost of federation is not very high (except, perhaps, i, edge cases like Beehaw where there is a very large defederated userbase with which users would like to interact)