pip already came up with a decision. see the link above.

Again I see that you are not able to read.

I guess you are not able to read.
Every single native packager for any single scripting language or other package system does allow installation of nonfree packages according to your terms, and would be thus as such banned from PureOS. Many of them already agreed to add a license meta field to their databases. So they are not hostile. You are the one who started the hostility against them.

So why are wanting to ban cpanm, and not the official client cpan out of the blue? You are acting completely irresponsible.

"A free system distribution must not steer users towards obtaining any nonfree information for practical use, or encourage them to do so. The system should have no repositories for nonfree software and no specific recipes for installation of particular nonfree programs. Nor should the distribution refer to third-party repositories that are not committed to only including free software; even if they only have free software today, that may not be true tomorrow. Programs in the system should not suggest installing nonfree plugins, documentation, and so on"

This is ridiculous. So you want to exclude wget or chromium also, because it permits downloading nonfree code?