Keep mind that Google was initially installed as the default search engine years ago, because FF users voted for it to be so. Only after Google saw how many search referrals they then got from FF, did they, that is Google, suggest an actual deal (which paid, incidentally, only a few percent of the market value for those referrals.). That deal doesn't include anything preventing users from changing the defaults.

Consider as well the Awesome Bar. The ability to search your history easily resulted in fewer users going back to Google and generating search referrals. Mozilla implemented it anyway, because it was good for the user.

You seem to be missing the point that overthrows your assertion. Yes, there is still a deal with Google, but Mozilla doesn't care if doing and advocating what's good for the user makes that relationship less and less valuable for Google. They are, in fact, sacrificing potential financial gain for the sake of their principles.

Mozilla has numerous, egregious faults, but this kind of hypocrisy and ethical lapses aren't among them.