It's not just direct rule of Imperial worlds. As the representative of the Emperor, the ArchDuke is more the "man on the spot" to talk to the Client States and Independent States. Client States have not sworn allegiance to the 3I, but are considered "protected" due to the economic ties. It is those solo non-aligned worlds that are risk takers with militant K'kree near. Might serve them right to get trampled.
GO MLPoD! Because friendship is not possible...:devil:
GO MLPoD! Because friendship is not possible...:devil: