DAr19...if MAG wanted to ban BA/BMI for a reason then they probably could. However, since the legitimacy of such an action would be against the EUs restraint of trade rules it seems unlikely that MAG have deep enough pockets to fund the court case and subsequent compensation claim.
Since 1993 the EU has operated as a free market for travel so an airport cannot ban travel between 2 airports unless there is a genuine reason.
Not really sure what you're babbling about with your SNCF example as you're talking about something completely different.
Bit less time in the sun, my old son.