There are only 2 ATCOs available for night duties at Cardiff, this does rather limit things when it comes to breaks.
Not sure if they were fully staffed that night or not but there comes a point when due Scratcoh people have to take breaks.
As for the loos, there used to be two very nicely positioned at the bottom of the tower stairs, then they were taken away from us and turned into storage cupboards. Now if one requires a natural break they have to go to the other end of the building.
I would very much doubt that would be the reason however for the place having to temporarily close, far more likely down to staffing issues or scratcoh