He says he is a vanilla mortal. The only supernatural about him is that he is a Venatori, so he knows of the supernatural but is not part of it.
He had some Wards on the cell but either someone else did them for him or they were ritualistic in nature, still, the only thing they did was detect magic use and make a sound, so something probably any Vanilla can do with the right knowledge. He later confirms that he can't do anything against spells aimed at him, so he is just a knowledgeable Vanilla.
Something else I find interesting:
just as the Thule Society was more or less a long-time foe, using their resources to attempt to use supernatural powers to their own benefit.
Seems odd to me that the White Council allows open opposition to them, even by lightweights. Luccio says that the Thule Gesellschaft has Sorceress in them later on, so they would fall under the authority of the Council. In the supernatural world of politics, aperance is a big thing (even more so than in the vanilla world), allowing some would-be-sorcerers to be in opposition, even if they don't break the Laws feels unrealistic.