What do you mean by “requiring the permission of others to use their client”

Which client are you referring to?

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That aside, trusting a person (Elon in your example) vs trusting a client (I assume you something like Damus or Primal)

Those are completely different for a few reasons

A. One is a person, the other is a piece of software (albeit written by “people”)

B. Nostr is a protocol much like http or pop3…the clients are just the UI to make accessing the protocol more user friendly

C. You (ie anyone) can make a client for Nostr…so you not trust yourself?

D. Using the logic you’ve laid forth, Bitcoin also would not be considered sovereign because it requires nodes to be in operation to progress the chain of blocks …much like Nostr requires relays

(and yes I’m aware that someone has solved a block or hash or something like that on a piece of paper…that’s an Outlier scenario)

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If I’m missing something or not understanding your initial post, please help me understand especially in light of my initial reply which was re: sovereignty vs trust