It sounds like he's simultaneously saying that it makes sense to reduce things to a common unit and that it doesn't.
Take the idea of the cost of a disease to the economy. That is applying he second "useful" principle exactly: reducing the problem to a unit that can be compared. If he doesn't like the implication that the problem with heart attacks is that they cost us money then he shouldn't be advocating for reducing everything to money. He may disagree with the way it was done, but that a question about the accuracy of the figure, not the idea of using the figure.
The level of intellect applied to policy debate may be low, but not for lack of economic principles.