AFAIK single-user instances are the best in terms of moderation for ActivityPub, if you want to join a Mastodon instance then that's your choice on whether you like or dislike the clique of moderators and their policies, and how transparently they're modified/enforced.

Mastodon, nostr, etc are like any interconnected network – censorship is seen as damage and routed around. The real big benefit nostr has is that identities aren't tied to nodes, so a node censoring any of their users doesn't also censor them from talking to other users/nodes.