All you friend has to do is contact reservations and they will re-book free of charge.
What is the point automatically transferring your friend if they don't necessary wan't to travel on that flight then they would be occupying a much needed seat.
Now placing an A330 on the route to try and get as many pax as possible to their destination is customer service.
Ryanair has about 230 aircraft in service and some of them may not be operating a full summer schedule. Plus a lot of standby crews.
Aer Lingus on the other hand has only about 40 aircraft with even less spare crews. The issue is there maybe spare crews available but the aircraft can't get into Dublin in time.
It is very complicated and i assure you they would want to get as many flights operational as possible as they face loosing money for cancelled flights due to refunds.
The more aircraft in the fleet the easier it is to try and alter schedules to minimise effect plus the more crew available.
It took over 48 hours for some airlines to get on track after the last time so what is so different now?
What you want Aer Lingus to do cancel flights before planned closures to make sure the aircraft are where they supposed to be? Then you will say why are they cancelling flights when others are operating.
It doesn't matter what they do it will never be good enough for your firend.