Considering Bruce Lee's One inch punch (push), locking out your front hand, from an un-locked out position, is a punch; because, you have provided the motion with body alignment. Your intentions are of no concern.May have even LOOKED like one to the judges, and the result was the same. But it wasn't a punch.
The mechanics were not that of a punch. It was simply the arm coming forward in a straight position as the hip was drawn back on the other side, with no intention to strike the other person.
FWIW, I didn't question the judges decision. But I DO know there was no intention on my part — I was concentrating on the reverse punch to his body I was about to throw.
Sean