Henry at CT.
If he’s being quoted accurately, Mankiw seems unduly defensive. If I were him, I’d take a much more pro-active stance. I’d claim that I was teaching my students a valuable practical lesson in economics, by illustrating how regulatory power (the power to assign mandatory textbooks for a required credit class, and to smother secondary markets by frequently printing and requiring new editions) can lead to rent-seeking and the creation of effective monopolies. Indeed, I would use graphs and basic math in both book and classroom to illustrate this, so that students would be left in no doubt whatsoever about what was happening. This would really bring the arguments of public choice home to them in a forceful and direct way, teaching them a lesson that they would remember for a very long time.
Yup, that would do it.