IMO that's only if you know about the book. If I hadn't read the book I would consider it as a statement showing the seriousness of their training (i.e., "this

IMO that's only if you know about the book. If I hadn't read the book I would consider it as a statement showing the seriousness of their training (i.e., "this isn't a game, we're training you for a war, so don't fool around and please take this seriously.)