With respect, this argument falls flat on it's face. Both Firefox and AMO (old and new versions) remain open source. The additional requirement of signed extensions allows Mozilla to exert a light increment in control.
- Adding digital rights management black boxes
Fair enough, I didn't like the additional of EME either, but I also like netflix, despite the DRM constraints. As a user I am ok with this choice, because it enabled me, as a user, to choose to either consume DRM content or not, while using the browser of my choice.
- baking in commercial software like Pocket
Yep, that one left a bad taste in alot of peoples mouths. It would have been better if an API had been published and more than one provider had been supplied (cough cough social API, looking at you).
- intending to abandon XUL for better security of non-technical users
Palemoon does absolutely nothing to protect it's users. The Palemoon devs and project leads never miss the chance to take pot-shots at Mozilla and the Firefox engineering team, but the only reasonable claim they can make about security is "Pale Moon is based on the Mozilla release source code that has a large community of developers and security-aware people, next to having seen over a decade of development by now."
The problem, which the Palemoon devs have now stated clearly, is that they can't improve on the legacy version of Firefox they forked, and even when I still worked there were only able to take up security fixes with diminishing capabilities due to deviations in the code base.
Finally, Mozilla is not abandoning an old ecosystem, they are making a substantial investment in building out a new ecosystem while providing tools, documentation and an upgrade path. I recognize that there are still people who like to use old software, but at some point you have to take a good solid look at things and think: ok, lets try this again and apply the lessons learned.
Palemoon is an insecure knockoff browser that leverages open source in all of the worst ways without giving anything significant back, and even worse, they weasel around what they are doing and make claims about performance and stability that are flat-out indefensible (not that they could prove it since they have no mechanism to collect the data outside of their own build machines).
And for all this they abandon power users. If there is a real shame for all Open Source, it is Firefox.
Your implication that he's calling it a unique new browser is either intentionally disengenous or confused. A "browser product" is a product made from an existing browser: Firefox. There's nothing in the linked post that presents it how you do.
Pale Moon's fork fixes some important ethical (and aesthetic) issues I have with Firefox's current direction. I'm glad that both (and icecat, iceweasel, etc) can coexist because they're open source. Re-forking from a later version seems reasonable to me since not that many people think the above issues are important. As the post said, there aren't enough contributors to keep up with the evolving web. Re-baseing from an acceptable later Firefox version would give me another few years of breathing room.
The only part of this I don't agree with is the existing Firefox extension ecosystem not being compatible with the new Pale Moon. But I guess as Firefox abandons them the value of the old ecosystem dimishes.