With Mu Niu's breakthrough, Lin Mu was assured that the Mu clan would be fine for the time being, even if he was not there. While Nascent soul realm cultivators were what Gu Yao had many, it was still not possible for him to just send any random one to target someone.
Especially in areas that were not fully under his control. If he did so carelessly, he would only invite the ire and attention of the ruling power of that region, which might spiral out into him getting revealed to the world.
After all, one must remember that even after the blood tide happened and he put the blame on Lin Mu the one who got the fame of repelling the blood tide was Wu Xun. Even then, Gu Yao did not want to reveal himself to the world and wanted to stay hidden.
Silently gaining power while controlling the great powers of the world, such was his plan. The emperor of the Great Zhou Empire was already sick and the court officials were now starting to get worried about it.
