Block/Player Control/No Call

[Zoochy]

B1 is tightly guarding A1. A1 has his back to B1. A1 receives a pass. Just as A1 turns towards B1, B1 starts to lean back(bail out?). A1 makes contact so that B1 falls (or flops) to the floor.
One official states that this CAN NOT be a player control foul because B1 is leaning back. B1 has lost his 'Legal Guarding Position'. Thus Blocking foul or Play on. Another official states that it could also be a player control foul because B1 did not do anything wrong. A player is entitled to a space on the court.
A) Block
B) Player Control
C) No Call/Play On
I know... someone is going to say "Had to be there to see it"