What's Mallard raving about today?
This reads literally as an indictment of children as dangerous free spirits. Which would definitely be the most curmudgeonly interpretation possible.
But it's hard to believe this isn't just another in a long string of indictments of the school system. Although that requires us to believe that, despite the fact that Mallard decries education standards, he views the lack of running and playing in the classroom, and preventing wanton trips to the bathroom to escape class as a flaw in the education system.
Of course, I doubt anyone actually cares which of those it is; what really matter is the question of how long he plans to keep up this rant?