Father…

The location of the Eternal Heaven was absolutely vital. When Shrek City was destroyed by two Godkiller-ranked fixed soul ammunitions in the past, it left everyone devastated including the Heartless Douluo and the Amorous Douluo. Even though the Tang Sect's Soul Circuit Defense System was built to defend against fixed soul ammunitions including Godkillers, the Eternal Heaven was reputed to be the most terrifying weapon in the history of mankind. The power of the Eternal Heaven had surpassed the combination of two Godkiller-ranked fixed soul ammunitions before. 

Who could sleep soundly when such a weapon existed?

With the development of technology, Limit Douluos and four-word battle armor masters were not invincible anymore. Even if the Atlas Douluo were resurrected, he would not also have the fortitude to resist the Eternal Heaven.