This is effectively the norm with more traditional, curated package managers. Say I release a piece of open source software, and some Linux distro adds it to their package manager. Under a typical open source license, I have no legal right to ask them to stop distributing it. They can just say "sorry, you licensed this code to us under X license and we're distributing it under those terms. Removing it would break our users' systems, so we won't do it."
The difference is that NPM is self-service - publishers add packages themselves, and NPM has chosen to also provide a self-service option to remove packages. I honestly wouldn't have a problem with them removing that option, and only allowing packages to be removed by contacting support with a good reason. (Accidental private info disclosure, copyright violation, severe security bug, etc.)