The Pixiv encyclopedia's page on Scirocco talks about him not being in GQuuuuuuX and gives a list of reasons why his presence would upset the balance.
>High piloting ability and Newtype qualities (ability to cause psychic hits) without ever having to wear a normal suit
>His technical skills allow him to hand-craft units such as the The-O and Messala .
>He has charisma that makes Yazan Gable say "That's interesting" and hit it off with him .
>Ambition to outwit Jamitov Hyman
>Research into immortality, such as preserving personalities and memories, using an advanced version of the Psycommu Grimoire, was conducted in the Ambrosia section of Jupitris.
>His idea is to make all mankind understand the ataraksia (peace of the soul) he feels through "Psycho Flare "Orpheus"" without any misunderstanding.