(SNIP of discussion of removing Gurthak from his position)
I would find it highly unlikely that should the commandery find need to do so, that they couldn't change out the commander on the spot. There could well be political consequences, but my wager would be that the authority for doing that would be there.
Actually, it looks very simple to me. They need a vacancy somewhere, but they promote somebody to fill that vacancy, move or promote someone else to fill the new vacancy, and so forth until Gurthak is assigned to a more prestigious post. Nobody has valid grounds for complaint.