Is the question whether this deal prevents companies from developing and selling their search solution? If so, then is Google paying Apple, who has what, 40% market share of mobile phones, really able to stifle the development of search engines? With search on mobile phones being a further x% fraction of all (general, browser-opening) search being done on the internet? I.e. when placed with desktop, tablet, browser window search as well.
If we're down to perhaps low double digit % of all search, how it that unfairly preventing competition?
And yes, if you then go to the opposite extreme and say that the market is search on Safari on iPhones, then the market is cornered and controlled by Google. But is that reasonable to define as the market in question? Where you're entitled to not have anti-competitive behavior? That's Peter Thiel's example of having cornered the market for British food in downtown Palo Alto and prevented competitors from moving into your rented space.
It may be a sweetheart deal for Apple, and Google making sure that it gets preferred treatment in this one corner of the internet, but it seems to me hard to claim that this has stifled competition for the development of search engines in general?