Huh? Google is not doing charity by paying Mozilla, the GP is off base there; they have a contract with Mozilla for getting to be the default search provider. There's nothing to threaten with. But maybe you're privy to some secret contract negotiations the rest of the world isn't?
Besides, there's a reason Google pays so much for that slot: there are others willing to pay a lot for it as well, and even more competitors if Mozilla is willing to take a smaller payment for it.
