Saint Lady had obviously researched Shao Lin before and was very familiar with him. She knew he had poor character. If he became an Heir, there was the risk that he could turn around and bite them.
In Saint Lady's opinion, Lin Yue was the best candidate. He was gentle, just, intelligent, extraordinarily talented, and loyal. He would step out when needed and charge bravely. He also lay low and didn't want to compete with the outside world.
Shao Lin was nothing compared to Lin Yue.
If he's already so disrespectful to me, wouldn't he be even more uncontrollable if he's allowed to become a Saint?
Saint Lady worked to push down her anger and remain calm.
After all, Shao Lin was now an Heir and would become the empress's disciple. Even though Saint Lady wanted to teach him a lesson, she couldn't do it so obviously. She couldn't leave any traces either.