The Ikea car park only has planning permission granted for ancillary car parking, as an adjunct to another facility. Not as a revenue-generating car park. It's like saying 'why can't I just use my house as a hotel, it has windows and beds!'
Regardless of the backroom lobbying, Mr Boal has been operating without valid planning permission and was well aware of this fact.
Yes I have no doubt legally you are perfectly correct, my point is that given that the infrastructure which is already established for a similar purpose (whether a car park makes money or not is not a great leap on paper) I think in a real world situation, approved planning would have been a pretty acceptable decision. That leads me on to your second point about lobbying. If you think Mr Boal was the only one lobbying, you must be crazy. There is a reason the airport is popular with Stormont....