i don't know...
the book makes a good point of stating "creatures...will have spent a certain number of action points in the course of their "heroic" careers", so even if a creature has PC class levels, that creature would have had to spend action points to get to that level
even if dragons had AP, they would have had to have spent some during their life (and i certainly wouldn't award points for simply sleeping their way to the next age category

)
i'm not sure i would use reputation either. it looks to me like reputation is a chance for
anyone to know who the character is. even in a modern version of a very magic heavy world (like FR), not everyone would know about any given dragon. there would be certain individuals and groups who would know, but not everyone. even if a particular dragon was terrorizing the countryside (or whatever), that doesn't mean that people in the next region know about it
the big difference would involve the media, but any relatively smart dragon would get the heck out of Dodge if the media was on their tail (they'd be hunted by everyone!)
another thing to keep in mind is reputation affects Bluff, Diplomacy, Gather information, Intimidate and Perform checks. does a dragon really need help in those areas?
