Well, here's the rule:
Rule 61. Slashing
61.1 Slashing - Slashing is the act of a player or goalkeeper swinging his stick at an opponent, whether contact is made or not. Non-aggressive stick contact to the pant or front of the shin pad, should not be penalized as slashing. Any forceful or powerful chop with the stick on an opponent's body, the opponent's stick, or on or near the opponent's hands that, in the judgement of the Referee, is not an attempt to play the puck, shall be penalized as slashing.
So the ref could argue that it was a forceful chop that wasn't an attempt to play the puck.