Yes, they should, but then, the designers don't ever seem to know what to do with monstrous characters and epic advancement. Presumably, a creature with a "character level" of 20 or higher who gains even a single class level should use the EAB and epic save bonus progressions; of course, this gets odd because a hit die of advancement would confer BAB and save progressions instead. One argument goes that creatures can pick up 20 class levels over and above their racial HD before switching to the epic AB and save bonus progressions; Savage Species put paid to that idea by explicitly stating that "character level" is racial HD + class levels. As such, it does look like a dragon with 20 or more Hit Dice who takes levels in one of these PrCs gets no BAB and no normal save progression. The designers might have figured that this makes the PrCs less attractive than just adding dragon HD, so they gave 'em BAB and save progression. So I guess it depends on whether you feel like adopting the PrCs in Draconomicon as an exception to the ELH, or following the ELH p.25 sidebar rules.
