Regarding the recent Nostr drama, I've seen this same censorship debate played out, and end, over on Hive (the old Steemit) for years. There, clients (called front ends, the main ones being PeakD, Ecency, hive.blog) censor out hate-posters and such. However, the posts are still there on the chain base layer and can be seen in any chain explorers. This would be like nostr notes on relays. Notes are there even though individual clients choose to not show them or filter out their author.

Bottom line, individual clients/ front ends can do whatever they want. Censor, filter, or show. It's their project. If you don't like the censoring or showing, then use another client or build your own. This is how decentralization works.