> 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 a set of guidelines (https://developer.mozilla.org/en-US/Add-ons/AMO/Policy/Revie...) for when it is appropriate to blocklist an add-on and have refused multiple times to block for other reasons.

Is Mozilla refusing to sign the add-on? Or just refusing to host it on addons.mozilla.org? There's a big difference. If the extension can still be signed, it's easy to install on production Firefox builds. If it can't be signed, then it can only be installed on Nightly or Developer builds with xpinstall.signatures.required disabled in about:config.