Martin St-Louis left to be with his son Mason at the end of the season, for over a week. He left the Canadiens, and it's completely understandable.
But Martin also has two other sons, including Lucas, who plays in the USHL. He dropped the gloves against a player who could very well be the Canadiens' next first-round pick.
Indeed, Sacha Boisvert is projected to go between the 15th and 25th pick, and the Canadiens happen to have the 22nd to 24th pick, if Winnipeg loses the next game against the Avalanche.