Not necesarily. There could be bonuses to having chaotic vassals that make even 1 extra vassal slot extremely valuable. Ensured loyalty for one, at least as long as the relationship holds, with his vassals taking leadership positions amongst the local chaos seed population. Probably some significant boosts for his tier 1 servants for serving a mighty being such as Richter. I'm also pretty much certain he will get a vassal slot per rank. He is a chaos lord, ranking up should strengthen the main aspect of the race.