Zhou Tian was a Human Emperor, and his enemy at the moment was also a Human Emperor.
While Zhou Tian possessed a certain level of rule-based cultivation, although the other Human Emperor was temporarily inferior, if he could fully utilize the conditions of the world at this moment, it was believed he would definitely grow to Zhou Tian's level. And if that happened, even though the rules they each cultivated might be different, the overall strength of that Human Emperor would surely catch up to Zhou Tian.
If that Human Emperor really did grow to that extent, Zhou Tian figured it would not be an easy task to take him down then.
Therefore, quite awhile ago, Zhou Tian had already become aware, no matter what, he could not allow that Human Emperor to grow, because if the latter did grow, he would then become a threat to him, and even Zhou Tian might eventually lose his life at the enemy's hands.