Chu Mu actually didn't know that Tian Ting would not suspect Mo Ye. It was because of an unintentional remark made by the elder.
When Elder Liu secretly protected Chu Mu and found that Chu Mu was being watched by Tian Ting, he immediately stepped in to stop it, declaring Chu Mu's identity as the son of the Soul Hall Honorable Lady and a young master.
The Honorable Lady had a transcendent status in the Soul Hall, and she also held a position in the Soul Alliance, as one of the Sixteen Extremes—Star Extreme. She was considered Tian Ting's immediate superior.
In order not to expose the matter, the Alliance Master assigned the inconspicuous Tian Ting to do it. If Tian Ting forcibly acted against Chu Mu, given the character of Star Extreme, she would probably not hesitate to destroy him.