Interesting scenario

[A Man for All Seasons]

Player A1 passes the basketball from mid court to A2 on break. A2 is standing outside the key, not moving. B1 runs with hands in the air trying to block A2's view of the ball. The ball hits the back of B1's hands and deflects out of bounds. At that point B1 had reached A2 and his hands were in front of his face. I whistle a T for a player technical. My partner comes to me and says he has never heard that called before. I told him it was under player technicals in the rule book. By definition was that the right call?