After witnessing Zhou Tian's strength, if that mine was not of great importance, those NPCs would have chosen to give up by then. And even if the mine was of crucial importance to those NPCs, so much so that they were unwilling to give up despite knowing the heavy cost of dealing with Zhou Tian, it was unlikely that they could organize an attack in a short period.
That being said, whether those NPCs would launch another attack on the mine or not, Zhou Tian would have departed early by the time they moved. And what response those NPCs would make later, Zhou Tian wouldn't care at all.
In fact, everything went smoothly. With the help of the dwarves, in only a day, Zhou Tian managed to fill a spatial ring with magic crystals. Although at the time, if he wanted, getting more magic crystals wouldn't have been a problem.
