As an EU citizen, could you not have gone through passport control to visit the "fancy stuff" without any questions being asked?
Originally Posted by
EUcitizen
I had to wait in the arrivals area for 5 hours for the connection.
Trains to Brussels typically run hourly so there is no reason to accept a 5-hour wait. If there was no option to get an earlier train in conjunction with the flight ticket, I would just have booked a standalone train ticket for €25 in advance (and if the flight is delayed such that you miss your separately-booked train, the 5-hour wait would be significantly reduced; or your flight ticket would end in AMS and you might get EC261 compensation).
There is also a €55 flexible ticket for any train on a particular day, though booking two €25 tickets at different times would be cheaper