I would imagine one of the demands is that they are excluded from using the Polderbaan runway. And does Schipol want or need the hassle that comes with Michael O”Leary’s budget brigade.
Lelystad looks like a much better fit for FRightmares business model.
Edited to add……
Early Sunday morning boredom has led me to do a wee bit of googling. And the more I’ve looked into Lelystad ,the more I’d favour that option if I was MOL. And because of the great rail links between Lelystad and Schipol, if I was sitting in the Schipol decision making seat I would consider this an opportunity to grow both airports in tandem .