My understanding with regard to the free train tickets is that it's a SEN initiative and has been offered to a number of airports as part of their marketing campaigns.
I had to visit Groningen for a few days this past week and returning on Friday evening had my fastest ever transit through the terminal. It took just 6 minutes from aircraft steps to the train station and that included baggage reclaim! The total travel time from the aircraft to Liverpool Street was 67 minutes. It was a quiet time of day but the speed with which the bags arrived on the carousel was remarkable - there just being some 25 pax on the flight helped of course.
I don't know if the DUB flight cancellations have been partly caused by the fact that EI-REM is still out of service following its engine failure early last week. I did see it reported as a turbine failure but cannot confirm that. The standby aircraft, EI-REH, has been operating on the SEN European routes in its place all week.