This is a pretty good hyperbolic rant. Nothing positive, all negative and an unsubstantiated "I can't prove it but I think they're doing this because..." which always gets the blood pumping and fingers flying. I give you an 8 out of 10. I could have given you a solid 10 on this effort if you had blamed the libs or a cabal for the nefarious deeds occurring in your about:config.
They didn't hide the release of the ~~bug~~ feature, they posted it on the Moz website for future patch notes.
The "for now" about the config setting actually made me chuckle. It's an option that you can optionally choose to disable. They're not testing their evil deeds on you by letting you turn it off.
Google is making their move because of their ad dollars at stake, Firefox will only benefit in terms of market share when that happens because they'll have another bump in user count in the form of a mini-exodus from Chrome, just like they did when Chrome announced stopping ad blockers from running in their browser. Almost all income from Moz comes from partnerships with the search providers listed in the browser search options. 0 dollars comes from advertising, so there is absolutely no reason for them to keep you from blocking advertisements on pages that only helps their competitor.
It's very clear to anyone that's paid attention that Moz is trying to protect a user that's downloaded a malicious addon(or one that's been hijacked) from siphoning data like login/pass on your banking site when, for example, the addon is supposed to only change the youtube site from displaying shorts in your feed. Prior to this ~~bug~~ feature, an addon that could see all data on a webpage could see all data on any webpage, whether it needed it on that page or not which is comically bad practice. They've finally implemented a method of restricting addons that don't need to see your most sensitive browsing from doing something nefarious like selling that data, using it against you or robbing you blind with it.
Here's the best part of it all though. Simply use a forked version of the browser if you feel you're using one now that an evil entity is trying to enslave you with by forcing you to see their competitor's advertisements(logic!). There's many "hardened" versions of Firefox, like librewolf, which strips Mozilla phone-home stuff like telemetry, sync, etc., The code is open source meaning you can build your own from the sourcecode, which will allow you to pore over every line, looking for hidden treasures that are trying to ruin your browsing experience. Or at least make an uninformed guess that is what it's doing.
This isn't news. This has been Brave's business model from the beginning.