The purpose Komaeda would have been proposing barriers for is to stabilize the emotions of anyone within them. They couldn't defend themselves as effectively if they're having so many mood swings. Monsters could be fended off by other means. It's crucial to him that mental stability remain. For the sake of the people and the Arehtei.

But to be clear, the giant crystal in no way directly stabilizes the Arehtei's emotions? It doesn't make it easier to maintain them except through the people on the island?

Her bringing up that her own power protected her city at least initially would prompt him to ask what is protecting it now. Just the mountain? Or is there something else there. He would add he would understand if for security reasons she wouldn't wish to reveal it. His interest is purely to find other means to safeguard the island and all within it.

He would further ask that to reconfirm that even in a broken state, the crystal itself stabilizes any area it resides in. why?