Suppose Saunders is right to believe that their superior, inherited, natural ability helps explain why children of middle-class parents are so likely to get middle-class jobs. How does that make the resulting distribution of income "unequal but fair"? Why should one person earn more than another simply because she happens to have been born with different genes?
Arguing that people should get jobs on merit is one thing: it helps all of us if jobs are done by those best able to do them. But permitting their good or bad luck in the natural lottery to influence how much money people earn doesn't look very fair to me.