Is this a step towards implementing Google’s same extension restrictions in FF, setting themselves up as the primary arbiter of adblock tools?
I wouldn't expect that:
Firefox, however, will continue supporting both blockingWebRequest and declarativeNetRequest — giving developers more flexibility and keeping powerful privacy tools available to users
https://blog.mozilla.org/en/firefox/firefox-manifest-v3-adblockers/
and
And even if we re-evaluate this decision at some point down the road, we anticipate providing a notice of at least 12 months for developers to adjust accordingly and not feel rushed.
https://blog.mozilla.org/addons/2024/03/13/manifest-v3-manifest-v2-march-2024-update/
So even if that would change (which I'd be very surprised by), it wouldn't happen for another twelve months, so plenty of time for outrage then.