A male dragon would be a son of a dragon......ergo Son of The Dragon and The Dragon could be used interchangeably.
While I understand this kind of logic, its actually fairly moot. The discussion had shifted to the etymology of Dracul and Dracula. There is an actual, literal, difference between the two titles (see my previous post).
Furthermore, in my limited research I discovered that the -ae suffix isn't gender specific. In other words, it could also be used to describe a daughter (i.e. daughter of the Dragon).