Is it trademark? Is HTTP or WebSocket are trademarks? Nostr protocol is licenced under public domain. https://github.com/nostr-protocol/nostr
Are we talking about some mythical businesses? Zebedee is doing it right now, but not for reasons you are claimed. It's only marketing. Anyway if they had developed the protocol and made a unique, outstanding client, I would probably use it myself and enjoy the ZBD universe 🙂
Unfortunately, ZBD doesn't work in Russia.