Earlier quoted context omitted.
I mean Firefox caved to support EME. This isn't the early days of the web anymore either, the enthusiasts are a small minority of global web traffic that this will probably succeed even with a large scale boycott.
I think in this case Firefox is in a different position: if it didn't support EME netflix wouldn't work. But in this case it could report "sure, this is a real user alright" by being its own attester, can't it?
Anyone can write their own EME plug in that writes the files to disk. But it won't have the keys of any trusted module, because the reason sites trust them is because they don't do that. So it won't get accepted by anyone. Same here.