The word "prohibit" should only appear in the Limitations section. You know, like "Use of aileron trim with the autopilot engaged is prohibited". Otherwise, I've never seen Boeing "forbid" or "prohibit" anything. This is really a social convention...in which, when you haven't got a good enough argument for why you argue some point, you default to a higher authority. Otherwise known as "appeal to authority", or argumentum ad verecundiam, a logical fallacy common enough to be discussed by St. Thomas and John Locke.
But it greatly warms my heart to see that my own training department is not alone in their ignorance of what this thing does and why...
