They literally wrote a blog post about how they're going to use this feature. In what way have they not "specified their plans"?
> I'm an extension developer myself. I'm not ok with a world where a tiny number of lucky extensions get whitelisted, while my extension and everyone else's extensions get silently, remotely disabled by Firefox
Ah, now I see the real concern.
Honestly, I'm not that sympathetic. Extensions have always been a potential security liability and anything that protects less savvy users when accessing online banking or other sensitive services is a good thing.
Heavy extension use is the hallmark of a power user. Power users can configure Firefox to enable these extensions (Mozilla has specifically said they plan to deliver more user controls in 116), so I personally don't see the problem.