If one did not believe in free will, one would not believe in rewarding or punishing people, including criminals. It is not fair, reasonable, or productive to reward or punish people if their decisions are the result of some mechanistic process, rather than a decision that they made born of free will. That would be like punishing the weather for a tornado. My guess though, is that Mr. Stephen Fry does not believe that we should let serial rapists go unpunished or just open up all our prisons. If he believed his own words, these are exactly the kinds of things he would advocate for, since morality can only exist in a world with free will.
