The people of Sikou Hall are all cultivators; if these cultivators were to rebel, what could Emperor Xu use to defend against them?
Put yourself in their shoes—if she, Sikou Yao, were Emperor Xu, she would certainly harbor doubts as well. Therefore, she understood very well Emperor Xu's current worries and concerns.
That he could still choose to collaborate with Sikou Hall under such worries and concerns was enough to prove Emperor Xu's determination to forge good relations with Sikou Hall and her.
Sikou Yao also took the initiative to say, "I understand the worries in Emperor Xu's heart. How about this: I, the Main Hall Master of Sikou Hall, and King Gong Cen, the Sub-Hall Master of Sikou Hall's Tang Sect, will represent Sikou Hall and the Tang Royal Family to sign a cooperation treaty. It will state that the disciples under Sikou Hall shall never interfere or be involved in the Tang Royal Family's graces and internal affairs. What does Emperor Xu think?"