Artemicion will explain that permission would simply mean for the Heroes to tell their Moogle it is alright to archive their letters. For Heroes to access the archive, they would just need to have their Moogle with them, as Mognet Employee they can certify they are Heroes of Light and have this right.

Biggs will reply that the requirements are what should be expected from the army, unless Sephiroth's world's army is really terrible. He needs to be healthy and physically capable, there are strict training hours at Esdham and the likes. Because they are Heroes of Light though, Wedge made sure they had arranged schedules and as such, do not need to be present constantly. He'll also say that life at Esdham is harsher. They live closer to the desert and are at war, so much of the comfort found in Aqures Ixen will not be found there.