How is Cassie uncle tomming lillian jean why does she think she is doing this?

Cassie uncle toms Lillian Jean by pretending to be submissive and obedient in order to protect herself and her family from potential harm. She does this to survive in a society that expects black people to conform to white expectations and to avoid conflict or violence. Ultimately, Cassie's actions are a form of self-preservation and resistance in a deeply oppressive and racist environment.