why do you suppose rudy got himself disqualified from the final race of the day and then left his medals behind?

Rudy spends the summer training for the upcoming Hitler Youth carnival, in which he intends to win four track competitions and show up Franz Deutscher, the Hitler Youth leader. Rudy wins the first three events but is disqualified from the fourth for two false starts. Later, Rudy tells Liesel that he disqualified himself on purpose and leaves his gold medals with her.