Zhou Tian could have easily left that world initially, but upon reentering it now, he estimated the living beings there would have a different view of him.
Previously, the living beings of that world had deemed it uneconomical to deal with Zhou Tian, which was why they allowed him to move around for some time. Even so, that was because Pan Shi had attracted most of the world's attention at the time; without Pan Shi, the beings of that world might not have been so easy to talk to.
But now, when Zhou Tian reentered that world, not only would there be no Pan Shi to draw the fire away from him, but Zhou Tian's action of leaving and returning was most likely to incite the enmity of the living beings there.