Foul Call

[Dbyb]

Watching a game just before mine. A1 goes up for a shot in the lane and there is contact by B1. The contact is a pure judgement call. I would have called a foul but I would not criticize others for not calling it. On the initial contact, the ref had nothing. The ball bounced around on the rim two or three times and then bounced off. At this point the ref called a foul. I asked the ref after the game if he intentionally held his whistle to see if the ball went in or not. He said yes, that's exactly what he did. The ref said if the ball had gone in, he would not have called a foul. Is this an accepted practice? For contact that is marginal but could be a foul, do others wait to see the shot result before calling a foul?