The White Bone Demon still left.
She had no choice but to go to the Dongsheng Continent to help Sha Chen and save her split spirit, because her cultivation level was the highest among Sha Chen's followers, and secondly, she was a Primordial Spirit Cultivator. She was also skilled at transformation, sly and unpredictable. She was a rare talent and the most suitable person for the task.
Truth be told, Sha Chen had no one else available, and he couldn't go himself. He had to make the best of a limited pool of talent and send the White Bone Demon.
After all, that split spirit held great responsibility, carrying treasures like the Golden Cloud Crown, the Spirit Summoning Decree, and the Netherworld Undying Sutra, as well as numerous Divine Powers such as the Eight-Nine Profound Art and the 72 Polymorphic Transformations. She was a crucial piece in Sha Chen's grand scheme, irreplaceable. Unless absolutely necessary, he wouldn't want to discard that split spirit.
