I think you're confusing the term monopoly and antitrust. Business can achieve monopoly with patents and intellectual property protection. They are only not allowed to buy out competition to achieve monopoly. Antitrust only arises in merger and acquisition, not from natural progression.
But that's besides the point. Apple is not even close to monopolizing anything. Remember, there's Windows owning 90%+ of the consumer market? hello? OSX has competition, OSX is a minority in the OS world. I think you got a context problem in framing what market you are considering at hand.
This thread....is similar to saying "Sony should open PlayStation OS to run on Xbox 360 hardware!"