Reset game clock?

[rbruno]

Just saw this happen in an AAU game last weekend.
Game clock is running down and the lead official whistles a foul just before the game clock horn signals for the end of regulation time.
The clock was a portable clock between the benches. The trail confers with his partner and has the table put one second back on the clock. This was a common foul and the offended team was behind by 2 points. The game ended with the subsequent throw in.
Is this correct? I know he didn't have definate knowledge of how much time to put back on....the clock did not register tenths of a second.
Should time have been put back on the clock? It doesn't seem right to just let the game end with the foul and no throw in when the whistle clearly preceded the horn and the possesion could determine the outcome of the game.