Why is klipspringer unable to refuse gatsby's request that he play the piano?

The real reason is that Klipspringer is his private piano player and he never left the party. Have in mind that Klipspringer is an uninvited boarder in one of Gatsby's many opulent guesthouses. Klipspringer is a very interesting character due to the fact that he is a shallow freeloader who seems almost to live at Gatsby's mansion, taking advantage of his host's money.