The EK 777 has diverted to PIK before, held on the ground, refuelled, then back up to GLA when it re-opened, much more convenient for all concerned I'd have thought, crew, and pax.
If the flying time is roughly the same, how is that much more convenient?
NCL is 3 hours away on a good day. At PIK you walk over a bridge and there's a train service to Glasgow Central every 20 minutes, 40 minutes away
Except on diverted flights, you just don't get off the plane and wander off to make your own way home.