After Uncle Hammer found out Stacey "gave" his coat to T.J., what lesson did Uncle Hammer teach as he reprimanded Stacey?

When Mama tells Stacey to get his coat back. Uncle Hammer, however, contradicts Mama and tells Stacey that if he is stupid enough to give his coat to TJ, then TJ can keep it. Uncle Hammer adds that Stacey isn't likely to survive long in the world if he allows people take things away from him.