One could make the case Firefox is trying to 'protect users' if they resisted or protested any of the user hostile standards you mention, but Firefox has implemented all of them.
It's just this case and this is not 'user hostile'. If they are going their own way there must be transparency, disclosure and reasoning. But in the bug reports they are denying it.
Okay, I'm not saying Firefox is trying to protect the users in this case. Based on [0], they care about following the standard, and they implemented a patch once they saw they were not compliant. About 6 months ago, the bug came back. With a charitable outlook, it looks like a bug they don't give much priority to.
When it comes to the bigger topic of standards, they are meant to increase interoperability. However, there are many ways to interoperability, and they can serve different masters. Seeing how standards are just codified behaviours, they are similar to law, and it's quite clear that law is not always good. Civil disobedience is widely recognized as a valid way to influence laws.
In this light, I would say breaking standards can be a form of civil disobedience, if the standard doesn't serve the regular, disenfranchised person.
One could make the case Firefox is trying to 'protect users' if they resisted or protested any of the user hostile standards you mention, but Firefox has implemented all of them.
It's just this case and this is not 'user hostile'. If they are going their own way there must be transparency, disclosure and reasoning. But in the bug reports they are denying it.