Why didn't Liu Bang eradicate Wu Rui, the king of Changsha?

Emperor Gaozu Liu Bangyi * * * sealed eight kings with different surnames, all of which needed to buy people's hearts in the war. Liu Bangdi's industry must be there, so he and Empress Lu used various methods to eliminate heroes with different surnames. Seven kings with different surnames were killed and abolished for various crimes. Only the King of Changsha, inherited by Wu Rui and his descendants, had a good start and a good ending, and became the only remaining king with a different surname (after five dynasties, he stopped because there was no heir). But in fact, Liu Bang did not dispel his doubts about Wu Rui, and repeatedly tested Wu Rui. After Sean resigned and lived in seclusion, he lived in Wu Rui's home. According to Sean's plan, Wu Rui saved his strength and began to keep a low profile. He ceded most of his territory to Liu Bang's children, gave some of his elite Qin Bing to Liu Jia, the king of Jing (Liu Bang's cousin), and arranged for Wu Yuan, the son of a concubine, to bring some of his family back to live in Fuliang Yaoli. Besides, Wu Rui died young at the age of forty.