Joseph had come to the North as an exchange student from the Austria-Swiss Union's Military Academy. Publicly, he was an exchange student under the agreement signed between Duke Alessandro and Durin, even possessing a diplomatic identity.
Privately, he had joined the Northern Doctrine, openly admitted through official channels. Regardless of the department, even if they knew there was something problematic about him, they couldn't touch him without sufficient evidence.
Moreover, Durin had granted him the rank of lieutenant, so even if he truly committed an offense, as long as it wasn't a major crime, the Northern Kingdom could only expel him.
Thus, hardly anyone bothered monitoring a troublemaker, let alone such a trivial matter as the young man sending his laundry to the launderette. No one would expect that those receiving him would be the newly appointed Secretary and Political Commissar of the Northern Doctrine in Copenhagen.