Even if they don't draw in new business so long as the operation isn't loss-making as a whole (when considering ancillary revenue created, rents from concessions etc and not just the flights themselves) I can't see the issue. As noted, plenty of other airports across Europe and beyond pay for airlines to fly there so running your own services isn't that different. I'd be more wary if this was Stobart Air's only activity, but as they have multiple aircraft flying around elsewhere and fingers in other pies it makes the whole thing far less risky than my St Gallen example or Manston.