Exactly when does ball become dead?

[letemplay]

Saw this play happen last night in high school playoff game..don't think I've seen it before or if it can actually happen:
B1 sets up to take a charge on hard driving A1 coming down right side of lane. Prior to contact, A1 dishes across lane to A2, then A1 drills B1 and we have a whistle and a block signal given by official on play. Meanwhile, A2 has received the pass and shot and scored. Officials count the basket, but give the foul to B1, and the ball back oob to Team A.

I can see this as a possibility if A1 takes several steps after passing the ball, so that the contact occurred after or at same time of A2's release. But on what I'd describe as a bang-bang play, how can there be enough time to complete a pass of about 15' across lane, and a catch and a shot? By this logic, if A1 had been guilty of a PC foul here, wouldn't we without question waive off the basket? Does ball become dead on the contact (foul) itself, or not until whistle? A late whistle could have also added to the problem here as the L and C were withholding momentarily.

6-7-5 (and certain applicable exceptions therein) seems to be referring only to fouls on the shooter. Is this really no different than a play where a foul occurs by the defense away from the ball, at same time another player is in act of shooting? Whole thing just didn't seem right.