[Jimmy C]

Ok, Hero, how about this?

Spoiler for Cradle Control System:

The person's not that important, it's the Relic. In the days of the civilization that built it, the Relic core is the control interface and is keyed to the person who commands the ship. In the present era, an artificial mage is the closest thing to this.
But that would mean Scaglietti would have to brainwash Vivio or force her to cooperate in some other way. Otherwise, she'd tell him to take hike after she took control of the ship.