It is not a fork, it is a downstream distribution. There are many examples of exactly this pattern: distributing a patched version of an upstream project and call it “CompanyName Project”, where it is a downstream distribution of Project. This is an extremely normal thing to have happen in open source. One prime example of this is Linux itself!
Typically downstream distributions (like RHEL) pay for a license to use the project’s trademark as part of their product or business name. This is part of the owner of the trademark protecting and defending that trademark. Issuing the license grants permission in a protective way.
When there is a trademark, and a trademark policy is established, I would be happy to revisit that. However, until then I’m not convinced changing the name will meaningfully satisfy the unhappy people in this thread. I’m also not super interested in being subjected to a different set of rules than the rest of the commercial actors in the space that have also been using Nix in their company and product names.