Baba's disloyalty is demonstrated in his rejection of Ali and Hassan, lifelong servants to Baba, who leave for their mountain hometown after Hassan is falsely accused of theft by Amir. It seems a more difficult task to prove that Baba has courage unless we consider his moral courage in maintaining his ethical stance in business dealings.
Baba dropped the stack of food stamps on her desk. "Thank you but I don't want," Baba said. "I work always. In Afghanistan I work, in America I work. ... but I don't like it free money."