Nostr provides censorship resistance via replication. You use multiple relays and hope they don't all ban you at once. But there is no way we can force a relay to not censor.
Relay operators will censor, almost all of them will remove spammy posts and CSAM.
I have never censored anyone and I don't plan to (because I don't operate a relay that needs it given it is not public access). But I develop the chorus relay and I'm writing the moderation code, and so I thought it would be useful to get community feedback on what that 'banning' process looks like. Sending the banned person a notification seems right to me, including a reason, and a way to download their data.