bxl-forever
It is used for Service trafic/Verkeersdienst but not—or no longer—acting as a police station.
https://www.mapillary.com/app/?pKey=4750445991691132

This explains why you will not find it on the official website of Polbru.

Perhaps amenity=police + access=no will work here.  This is how we handle Federal Police buildings.