Since when does the Commissariat care about the PDF? The PDF is on the bottom of the totem pole.
Plus Commissars are only attached to the Imperial Guard and Navy.
Unless your name is Marius Hax, in which case you have the Chaliced Commissariat policing your PDF (Inquisitor's Handbook
, pg. 60). Still, your point stands, and the Chaliced Commissariat has had at least one run-in with the actual