Maybe so, but I disagree that Hydaelyn was so drained shielding the player from Ultima that She 'no longer can assist the adventurer beyond that point' - She's clearly seen doing just that, She pulls both the adventuer and Lahabrea into her realm where the player reprises the very first scene seen in the game (where they use the Crystals of Light to form the 'Blade of Light'), thus driving out Lahabrea from Thancred, then summons the players allies (Cid, Alphinaud, Minfilia et al) to go all Captain Planet on Lahabrea to resoundingly defeat him.