If Ubuntu does that, the problem goes away, because users who want only local search don't have to do anything, and users who want global search can turn online search on/off at will by clicking a toggle button right there on the Unity panel.
No it doesn't. Ubuntu's "problem" is that it's not making any money, at least not enough to support the 500 employees it has. Making it non-default will kill 99% of the revenue from Amazon since hardly anyone(not enough people to make money on) will go out of the way to click the toggle button.
Theoretically a company can get around this by offering a commercial enterprise on top of their free project, but that's harder to pull off, especially if the point of your project is to offer a good enough open source environment that people want to use it.
They could put a special plea on the install screen for permission to enable all the search functions. That might get a large number of folks clicking OK to enable these while still giving informed consent.
I think it's time to research other ways of keeping the lights on.