I believe he means that packages aren't namespaced (owner/package-name), so if I publish a package called nike, Nike could come and want to take over the package name.
Global namespacing has nothing to do with that. Even with per-user namespacing, there's nothing to stop a user from making their username "nike" and publishing all their code under "nike/package-name", which would be subject to just as much potential legal action as a package named "nike" itself. Likewise there's also nothing to stop Bob from uploading "bob/nike".
If course global name-spacing has something to do with it!
What's the difference between a "username" resulting in nike/package-name and a package called nike-package-name?
Not much in practice. Name-spacing doesn't mean "add another made up name entry somewhere".
That's why people who thought about these issues out-sourced this concern completely: Prove your ownership of nike.com and you can publish as nike.com.
Suddenly 99.9% of the trademark issues are gone, handled by registrars.
I think this approach is pretty obvious and I find the lack of thought coming from rust devs deeply concerning.
I'm not sure what you're trying to say. The problem exists independently of whether or not global namespacing is implemented by a package repository. Nike would have just as much authority to remove a "nike" package in a global namespace as it would to remove "bob/nike" (which is to say, almost no authority whatsoever).
I have no dog in the fight over whether or not a global namespace is a good idea, but it's tiresome to see irrelevant arguments being trotted out against global namespacing.
It wouldn't likely meet the standard of "confusingly similar" unless you called it "Nike" in order to somehow leverage the actual shoe brand (logos 'n all). But even if it didn't, you could imagine an index operator succumbing to the (unreasonable) request of a lawyer in order to avoid a conflict requiring representation.
(And I'm not sure what that has to do with namespacing.)