Since I am a utilitarian, I found what he said interesting. He offers several reasons why a utilitarian might accept such a principle.

For example, he points out that John Stuart Mill, the author of Utilitarianism, valued a certain kind of personal growth. Furthermore, Wong believes that 

When an individual's freedom is restricted in such a way that it cannot be justified to him or her, the kind of growth that Mill thought to be essential to well-being is frustrated. It is reasonable to lay down the justification principle to protect the general welfare. (Moral Relativity, p. 184)

He adds that "sympathy, compassion, and concern for another for his or her own sake may give rise to reasons for accepting the justification principle."

I wonder if Wong is on to something here.