[NFump]

PBUC 4.12 Batter interferes with catcher's throwback to pitcher:
Paragraphs 3 and 4: If the batter interferes with the catcher's throw to retire a runner by stepping out of the batter's box, interference shall be called on the batter under Official Rule 6.06(c)
However, if the batter is standing in the batter's box and he or his bat is struck by the catcher's throw back to the pitcher(or throw in attempting to retire a runner) and, in the umpire's judgement, there is no intent on the part of the batter to interfere with the throw, consider the ball alive and in play.

PBUC 4.15 Thrown bat interferes with fielder: If a whole bat is thrown into fair territory and interferes with a defensive player attempting to make a play, interference shall be called, whether intentional or not. However, if a bat breaks and part of it is in fair territory and is hit by a batted ball or part of it hits a runner or fielder, play shall continue and no interference shall be called.

PBUC 4.18 Thrown ball strikes helmet or bat: If a thrown ball strikes a helmet or bat accidentally (no intent on part of runner to interfere) in fair or foul territory, the ball remains in play the same as if it had not hit the helmet or bat.
If, in the umpire's judgement, there is intent on the part of a base runner to interfere with a thrown ball by dropping his helmet or bat or by throwing either at the ball, then the runner would be out, the ball dead, and runners would return to the last base legally touched.

T'would appear to not be interference according to the PBUC manual(which the Class A umpire was going by). So, evidently(as he was correct), this was not the reason he didn't move up. Could be why someone else didn't though.