Squaring to Bunt

[cjs]

At a recent game, players were squared to bunt. They never pulled the bat back. When I asked the umpire what the call was, he said that they could square to bunt and as long as they did not attempt to bunt the ball it was not a strike. My thought was that when they squared and put the bat over the plate that that was an attempt. He said, No. If that is right, why do coaches tell the players to pull the bat back??