They gave up on Aurora this despite the fact that Aurora was important as a major outpost of their invasion of worlds and possessed the resources needed for gem nobles to advance to gem kings.
For them, the loss of Aurora is a low price to pay to prevent the plague of war that this powerful invader brings with them everywhere they go.
Of course, not every gem emperor was in support of this decision. Some of them wanted to bring the fight to the invaders. But the majority of gem emperors agreed to seal off their homeworld and fortify it for invasion.
They also didn't tell the gem kings in Aurora that they were on their own forever. They told them to hold on for one year before they can get reinforcement.
This wasn't a lie. If the gem kings in Aurora perform well, then the council of gem emperors will have the confidence to fight the invaders and reinforce them.
