I understand what antitrust is, the one that doesn't understand what FTC is for is you.
Did you read the link? It's not a merger between competitors. There are no claims of price collusion between competitors. And Eric Schmidt himself claims Android phones are out-activating the iPhone 4:1, so it can't be an abuse of dominant market position. So what, exactly, is the DoJ supposed to investigate?
Do you think you can just march into any store and demand they carry your product on their shelves?