* Assuming that the NY High School Contest was being played under NFHS rules...
NFHS 2-9-1
..."It is considered a catch if a fielder catches a fair or foul ball and then steps or falls into a bench, dugout, stand, bleacher or OVER any boundary or barrier, such as a FENCE, rope, chalk line, or a pregame determined imaginary boundary line from the field of play.
Here is the rule. The batter was incorrectly awarded a home run.