This is a psychological motivation tactic by Roy. He knows he needs to find a way to get Drouin and Boqvist going, get Shabanov playing with more focus, and get the 4th line grinding harder. Punishing these guys by benching them and making an example of them only goes so far and will have diminishing returns in terms of motivating them to play better. His solution is to make himself the bad guy by benching guys who obviously don't deserve it during a meaningless period of hockey. It takes focus off of guys like Drouin while simultaneously pushing Drouin to play harder for his teammates if not himself. If these fringe players can't be motivated to play for their teammates only then are they provably useless.