I don't want to be a killjoy but I really cannot see Stobart becoming involved. Surely they have enough on their plate at the moment with continued investment at SEN (the terminal extension) and a large sum needed to redevelop CAX as per the recently granted planning consent. They would need the support of institutional investors if they wanted to add a third airport to their portfolio and I doubt that would be forthcoming.
If they have any spare cash, which I doubt, they would more likely use it to support Aer Arann's ATR-72 re-equipment plans as that would be of direct benefit to both SEN and CAX.