The Forbidden Ultima Core...
If there's something that the God Emperor valued a lot, even more than his own people, there's no doubt that it would be this.
Simply put, this core is the key to everything. It was the reason behind their rise and their evolution. It is the very source of their strength and it is the very thing that kept them going.
Augustus placed so much importance on the Forbidden Ultima Core that made an edict that aside from him, nobody's allowed to enter the room where it was nor even think about using it. This obviously includes the people who built the damn thing in the first place.
It had to be known that the God Emperor had no inputs on the creation of this thing. He didn't help nor even bothered. He hadn't spared a single idea to contribute for it's creation nor developments but he had the audacity to claim the thing as his.