I think it was clearly designed for a couple reasons. Cal is off screen, but the players on the court look in his direction when Naiper's holding the ball at midcourt as if to observe a signal. And then Young made his move with 10 seconds on the shot clock - as if the clock was the cue to run the double.
A hyperactive guy might have left after Harrison poked the ball free thinking there might be a loose ball, or possibly brought help too soon if he was the closest defender. But Young was 40 feet away, and had to pass by Boat and his Harrison (defender) to bring the double. It is possible that Poythress didn't hear/see the signal and didn't react properly. There was never a timeout called, so perhaps they needed a chance to get organized (but final minute of a NC, you better figure out a way to be organized).