The only sensible option for PIK is for it to abandon pax flight and thus lose all the associated costs i.e. close the pax terminal completely and concentrate on being an mx base and maybe freight etc.
The Traffic Distribution Rules were declared illegal in 1989 at The Court of Session, I don't imagine the SNP would see any upside in tinkering. It's way too politically sensitive in Glasgow and Edinburgh. You make a good point about passenger traffic. For me, the key is getting some up front development money to put passenger traffic at a cost base where it's profitable or revenue neutral to keep working with Ryanair Remember they pay parking fees over the winter for a fair whack of their fleet and have four bays of hangar space on Apron H. However they're currently using a terminal built in the 1960s and designed around long haul traffic, something less maintenance intensive and more basic may be needed.
Knock the old cargo sheds down and put up a basic tin shed passenger terminal with access to the railway and remove the current building before it finally blows away in a winter gale.
What can a new owner (and moreover one subject to EU State Aid Guidelines) do which the existing owners can't, and which isn't just playing a zero-sum game with traffic at GLA? (Genuine question.)
The previous owners allowed costs to spiral, using the previous model of having retail and core services in house and tightly controlled is not beyond the wit of man to achieve.