It was highly likely that the space of the dungeon was locked and its communication jammed. Thus the reason for the chaotic message the Demon Lord of Envy showed them.
At that time, he still believed that he had enough time to grow his dungeon until it became a behemoth kind of existence that couldn't be toppled down easily. However, the recent events told Simon otherwise.
He cannot let his guard down even for a second. Although there is no proof that the things he discovered in the underground chamber of the criminal organisation in the tower town are connected to those people who are responsible for conquering the dungeons, in the case that it is, he needs to be prepared.
On that note…
"Mars you did an excellent job by cornering the prey and discovering their plot in the underground chamber. Bea you too. Just as I said before, I am willing to grant any of your wish. If there is anything you want, don't hesitate to speak up".