>>Is this a way for Mozilla to censor add-ons they don't like, enforce copyright, government demands, etc.?
>No, the purpose of this is to protect users from malicious add-ons. We have clear guidelines[1] for when it is appropriate to blocklist an add-on and have refused multiple times to block for other reasons.
Copyright, DMCA, and legal concerns are not listed. So I take that to mean nothing will be rejected from signing for those reasons. Hosting on AMO has stricter rules, so they could sign the extension for you to host, but refuse to host it themselves.
Today, Mozilla doesn't get demands to take down extensions because sending demands would be pointless. If EvilCorp tried to force Mozilla to take down uBlock and friends from addons.mozilla.org they would just get hosted elsewhere and EvilCorp would look like assholes. It's all downside, no upside, so EvilCorp don't even bother to ask.
If tomorrow Mozilla can shut down any extension, the calculus changes. Forcing Mozilla to kill ad blockers still makes EvilCorp look like assholes, but it might be successful. There's a big upside now, so much more reason to try and force Mozilla's hand.
