You are describing the entire web, not Nostr alone. There is nothing in Nostr's design that makes it more resilient than the web, aside from using keys as identities. The rest is exactly the same. You put your data on web servers and hope other people can access and share it. Relays can censor you, DNS can censor you. Apps can censor you. So, yes, the web is fully open, and if you host everything yourself, you do have more control. But Nostr didnt provide that, DNS did. And if you need any other computer on the web to help you find or distribute data, you become censorable again.

The problem is that almost all of the parties you mention (clients, relays, media servers) are running at a loss, at least without grant funding in the picture. A good client takes at least one dev to maintain, and that's one dev's fair compensation, with some clients running full teams and a hefty amount of in-house infra on top. Many relays are running at a pure loss, when you look at infra costs, as well as spam and CSAM mitigation etc. If you add at the cost of incorporation and licensing, which are being almost completely ignored by multiple parts of the system, this only adds to the list. So in the end what can end up being the censor is simple economic reality. If grant funding stops tomorrow then economics steps in and says "you play by my rules now". ActivityPub is different because it can actually run on its own financial steam. BitTorrent as well, it has the financials worked out. But Nostr is still at very high risk of being censored by nothing more than the need for humans to pay rent every month.