1. The ball was in the hands of the player JB wanted to have the ball. It was never leaving his hands except to shoot. Robey had no opportunity to affect the play in a positive manner. I'm quite certain, as someone who has watched him bust his ass down the court on every other play, that he was told to hold back. No reason for the rebound to end up in the wrong hands. Had he run down and gotten position, even if wide open, time would have expired if Gillon had passed. There was no time for a putback as you suggested earlier.
2. See above.