[SAump]

U1 had no business asking, but U2 had no business calling that a balk. A throw to an unoccupied base w/ R1 leading off 1B is a balk. But the second R1 turned and ran toward the unoccupied base legalized the throw to an unoccupied base for the purpose of making a play. R1 is out. I would not reverse the expected outcome of a properly executed defensive gem unless I was absolutely sure that R1 had successfully stolen 2B. From the OP, in my judgement R1 was a sitting duck and the play shall stand.

Now I would like to know how the guy who incorrectly called a balk is going to enforce the one base awards after being set straight by U1? This would be especially difficult if the pitcher made no motion associated with the delivery of a pitch, ala start and stop.