Pitcher Throwing to Unoccupied Base?

 
With a runner on second base (R2), the right-handed pitcher is in the set position. As the pitcher starts his preliminary pitching motion by bringing his non-pivot foot back towards the pitching rubber, R2 breaks for 3rd base. The pitcher sees R2 and instead of delivering the pitch, he steps directly to 3rd base and throws to 3rd. R2 stops running half-way between 2nd and 3rd base and successfully returns to 2nd base. What is the call?
 
Call
When a pitcher throws to an unoccupied base, it may appear to be a balk. However, a pitcher may thrown (or fake a throw) to an unoccupied base as long as the umpire believes that the pitcher judged that he had a play there (even if the runner stopped). In other words, if the runner created the impression that he was stealing an unoccupied base, the pitcher can throw to that unoccupied base (no balk).