The passenger will have made their contract with the tour operator, not the airline.

The tour operator is responsible for the actions of its contractors (e.g Onur Air)

Therefore the passenger needs to take up what happened with the tour operator. There should be some reference within the T&Cs of what the tour operator considers itself responsible for.

The only question to be asked, is whether Onur Air contacted the tour operator to advise them of the diversion as they would have been well aware of the eventual destination (presuming the flight deck crew had made themselves aware of what was a scheduled closure…)

As the aircraft would have been due to take a return load of passengers, how did they get from EDI to GLA?