The Grand Marshal had freed spreads a few hours before the Hell fires, and a lot had transpired in the Imperial Palace. During the conflict against the Zerg Race, the troops released the inmates from the subterranean jail once it was determined that they would abandon the Imperium Star. Even the Queen Mother, who had betrayed the Imperial Family, had been released. She departed as soon as she was given permission to seek for her kid.
The Sentient Beings in the Lost Forest's Hidden Garden triggered a formation to transfer themselves elsewhere in space. They did not contribute to the resolution of the conflict between the Zerg and Human races. Their refusal to participate in the conflict demonstrates their position. They were devoted to the mission assigned to them by their monarch. So they had no choice but to depart Imperium Star ahead of schedule. They vanished in the midst of a conflict.
