Would it be big enough? Easyjet had to convert one of the hangar aircraft bays into mezzanine floors for offices. They also operate their academy from a separate building and run a fleet of buses between the two and their car park so I guess they would like to occupy just one building
Moving the airport HQ building to Signature terminal two would make sense as no doubt the bosses don't like having to queue to get out of the CTA with the common man. Find it had to see how viable a small hotel would be within the CTA. Most of airport hotels start from around 120 rooms spread over several floors on large pockets of land.