Sam is currently observing outer space. Well as you know some time ago he felt the presence of those prime Dragons. So there could be a possibility that those Monsters try to attack once again. Even though those types of attacks would not kill every living being of Eden Blue, at least all those normal people and those Warriors who did not have the capability to defend against those types of attacks would immediately get killed.
Because of this, Sam decided to observe outer space. All this time he was using the concealment technique so that nobody could find him. There could be a chance those monsters would not show themselves if they felt his aura. Because of this, he hides his aura.