Undoubtedly, when Zhou Tian was ready to depart from the traditional power system, the importance of the Territory to him at that time was not as significant as before. Zhou Tian used to care about his Territory because the amount of Territory affected his strength. If not for this reason, Zhou Tian, enjoying peaceful days, would have been foolish to continuously provoke 'neighbors' around him and ultimately make enemies on all sides.
Now, from the perspective of Zhou Tian's developmental route, the gain or loss of Territory was no longer very important. Yet, if Zhou Tian truly let those Ancient Ruins Spaces he occupied be taken over by Pan Shi, that wouldn't do either.