I mean (from Wikipedia/US antitrust law) "they restrict the mergers and acquisitions of organizations which could substantially lessen competition". Last I checked there are dozens of navigation apps and companies there, and by dozens I really mean nx12. Plus, it's not like "the" two market leaders merged to monopolize the market (i.e. "they prohibit the creation of a monopoly and the abuse of monopoly power"). Overall, I really don't see much of an issue here, aside the fact the Google managed - again - to buy something useful, which some of their competitors probably aren't that happy about.