It's also mentioned in Circular Altruism.

This matches research showing that there are "sacred values", like human lives, and "unsacred values", like money. When you try to trade off a sacred value against an unsacred value, subjects express great indignation (sometimes they want to punish the person who made the suggestion).

My favorite anecdote along these lines - though my books are packed at the moment, so no citation for now - comes from a team of researchers who evaluated the effectiveness of a certain project, calculating the cost per life saved, and recommended to the government that the project be implemented because it was cost-effective. The governmental agency rejected the report because, they said, you couldn't put a dollar value on human life. After rejecting the report, the agency decided not to implement the measure.

Trading off a sacred value (like refraining from torture) against an unsacred value (like dust specks) feels really awful. To merely multiply utilities would be too cold-blooded - it would be following rationality off a cliff...

I'm sure there's a hint in there, but I don't know what it is.