The airport have no jurisdiction on who goes where. This is not a banana republic. In the EU, any EU airline can go wherever and whenever they wish. The airport may provide some form of economic "honeymoon" but unless they want to face the wrath of established operators, this will have to on a measured basis.
PM
Newcastle Airport charge airlines for servicing their aircraft, landing fees, use of facilities, passenger service fees, (immigration, border control etc...) are all charged for. However LCC, especially,often want the airport to subsidise or waive fees for bringing extra services, and threfore passengers, to spend money in the airport's retail & catering facilities etc...
As a result some airports with high number /%age of Ryanair flights for example have low profits.
Newcastle maintain a balance of approx. 1/3rd each of Full Service Carriers / Leisure Charters (TOM/TCX etc..) / LCC (EZY/LS/FR), which keeps a healthy profitable business model.
I guess NIA don't "refuse" carriers, but they will not waive charges for LCCs when Full service and carriers who are prepared to pay airport charges, flying to the same destination would then incur higher costs and possibly withdraw. Norwegian may want too much from NIA to start services. Lot of history re. Ryanair in the past telling airports to drop their charges or they would withdraw services. NCL have a healthy mix, with opportunities for airlines to start services and pay the airport their due fees.