Eh yeah, killing the #1 reason why people still use your product is pretty much off-mission yes. I don't really understand how this would make money for them but either way it is the worst idea possible.
I understand more that he wants to be all in on AI. It's the big thing now. Billions are splashing around and Mozilla badly needs money. But everyone is doing AI browsers now. What would make Firefox so different from the rest? What is their moat? Better to focus on what makes it different rather than trying to play the same game as everyone else.
And yeah the web is in an existential crisis, but that's not really up to Mozilla to fix. I definitely won't stop adblocking that's for sure.