The Fediverse has the whole model backwards as a result of its design. Either individuals need to run their own instances, or identity needs to be completely ephemeral and flow through many servers as it does in Nostr. A Nostr admin can choose not to host data from a given identity, they could even use an identity whitelist, but users normally subscribe to multiple relays. In the end, the data gets through, while the relay admin can keep their own hands clean if they have a problem with the data.
Note that having this freedom does not preclude you from voluntarily signing up for blocklists. But this is an active choice, and it can’t be suddenly imposed on a set of users.