Not surely that's entirely correct. I believe that the terms of the original sale by the council to National Express required that the park and the airport could not be separated - to protect the airport from being closed down and turned into a business park.
So I think that while MADL have management responsibility for the park it is still legally owned by Bournemouth International Airport Limited. Certainly that was the case when I last looked at that company's accounts a couple of years ago.
I also think that MAG is prevented on this basis from selling the business park and the airport separately.