The Angry Marines have a Commissar because Fuklaw was too damn angry to be put anywhere else. After the Angry Marines saw him in action, they started recruiting from his homeworld.
Also he fucks impostors, fucks heresy, thinks that cover is for pussies and is a real paranoid psycho.
DRIVE ME CLOSER! I WANT TO HIT THEM WITH MY SWORD!
~ Commissaire Fuklaw during campaign