Ye Mo wasn't afraid of Shi Taa because his formation flags were hidden in the void. It was a level nine formation he created himself too. Even if Shi Taa was watching here, he might not be able to find it.
Plus, Shi Taa set up his formation normally, meaning that Shi Taa didn't notice his formation or didn't take it into consideration at all.
After Shi Taa left, Ye Mo went into the storm center for body refinement again. At the same time, he told Di Xueming to not look for him. He was afraid that Di Xueming would crash into Suo Anshan when he came.
Shi Taa told him to leave some marks and Suo Anshan would be able to find this place in at most three days. But before the end of the second day, Suo Anshan's people found where Ye Mo was.
There were three truth realisation state cultivators; they immediately surrounded the storm center and sent out a message.
