Federation is a revocable privilege contingent upon instance staff maintaining a community that other instances feel safe connecting to. If staff fails to meet that obligation, the privilege is revoked. This allows moderation to scale across millions of users.
If users are unhappy with their social circle getting broken, they should demand better from their admins or choose an instance that aligns with their values.
Instances aren’t just infrastructure and vanity domain names: they’re the building blocks of communities, and their moderation actions—including defederations—are affirmations of shared community values.