i think that a few sentinel enforcers would be fine,theres no reason why there shouldn't be some. honor guards are meant to guard prophets so i don't see why there would be any. as for councilor elites, why not? it would make sense for the high ranking elites to go to the "sacred ring". drones and brutes were added to the covenant after the destruction of the first ring, but that small detail doesn't REALLY matter to the story.