\nNing Shu really didn’t want to join Immortal Sect.
Xiao Susu wanted to change her fate. She didn’t necessarily have to stay in Immortal Sect in order to do that. In fact, she was at higher risk of being exposed if she stayed in the sect.
It was better to be eliminated from the selection entirely.
Xiao Susu hadn’t requested for her to deal with Lord Qing Hua, so she should leave him for Xiao Susu to deal with once she came back.
Xiao Susu wanted to become strong. Strong enough to rid herself of the pain caused by her bloodline and rid herself of the shackles she was bound by thanks to that blood.
That made Ning Shu’s task much simpler.
After leaving Immortal Sect, she should find a way to get rid of the seal on her body. As long as the seal was on her, her life would still be in the hands of others.