After explaining to all the guardians he trusted, they all went their way into the mortal realm. Since he has all the power to changed everything, he never used it to intervene what needs to be done right away. Just like the case of Eugene. He does not want to mingle with his business or to let the newborn fulfill everything he wished for.
As a Ruler of Kaluwalhatian and in charge of the mortals, he never once interceded for the sole of purpose of protecting his realm. What he wanted was peace and happiness for the entire Kaluwalhatian. In Sitan's case, he has all the more reason to stop him to ruin his plan or end his wicked intention. He let time and his trusted angels to do their job to prevent chaos on earth.
While he watched all of them flew and changed into a ball of pearl forming
