Now, let us backtrack to when Arthur, Layla and Nicole first arrived at the cafeteria and caused a commotion with their new realms of existence and go over some certain things once again.
Layla and Nicole never bothered to hide their realms of existence in the first place, as for Arthur, sometimes he did, and sometimes he did not.
He decided to adjust the settings for Creusery's concealment ring to show him being in the inferior stage of the grandmaster realm.
Besides his mother who helped him advance the night before he exposed and battled Owen, and Layla who saw him the next morning, no one knew he was actually an intermediate-stage grandmaster and not an inferior stage.
His true reason for doing this was quite simple; He was getting tired of hiding his energy usage even though he was obviously doing a sloppy job at it.