Besides the point that summer has made about whether or not morals come from god, he has made an entirely subjective argument stemming on the fact that he believes good fiction must deal with the concept of right and wrong. Good fiction can be about an introspective journey, or it can be about overcoming adversity. Good fiction does not require dealing with right and wrong.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell