It would make a lot more sense that way. At the moment it always seems strange, when you look up a faction and the summonable heroes are lined up right with the recruitable.
On that hand, I think the same should apply for heroes that are summoned with some hero-ability. In Ered Luin for instance Fili and Kili, who are summoned by Thorin, are shown in the hero list, but all the other members of the company, which are summoned are in the description of the hero that summons them.