Don't Understand !!

[just another ref]

In an 8th grade boys game early this year, the following happened: Tie game Team A inbounds the ball in the backcourt with 4.5 seconds left. B puts on a little pressure, does a good job of it and just about runs it out.
A heaves a long pass downcourt where A1 steps out to meet it about the 3 point line. A1 catches the ball just as he is plastered by B1. I whistle the foul. The clock stops on 00:00 and we hear just a hint of the buzzer. A1 steps to the line with the lane cleared, hits the first shot, game is over. B coach throws a minor screaming fit, at his player, not at me. "What were you doing even close to him???!!!" A1 had absolutely 0% chance to catch and then get off a shot. According to the logic expressed here, do I pass on this call? This was certainly a definitive case of the defender bailing the offense out. Do we judge what is a silly play and penalize the offense by ignoring it.
What if the player had lost the clock and made this 70 heave with 6 seconds left. The foul deflects the ball but the heavers teammate scoops it up and lays it in. Now who got penalized? You see a foul, you call a foul, the timer keeps the time.