When I was looking at the Flea entry, it states his species as "Human"... I was always under the impression Flea was a Mystic like Slash and Ozzie. It would be strange that they find Magic Using Humans to be extremely rare, yet they would have two of their own (If Magus counts as human).
I would leave it open to discussion for whether or not Flea is human or mystic. Flea's game sprite seems to have a much more different complexion than any human character (Save for Zeal people) even if Flea's official art seems to favor a human-appearing skin tone. The pointy ears are not human either, but again, Magus has pointy ears, even if none of the Gurus (also Zeal) do not. It is not clear whether or not Queen Zeal or Schala have pointy ears, but... I leave this interpretation up to you.
The question boils down to whether Magus is human or Flea is human... if Flea is human, then that provides a whole new interesting context to Flea's character... after all, how many magic using humans are there and, if so, how did he/she get to be a top commanding general in the Mystic fight AGAINST humans. This also raises the same question for Magus.
Perhaps all Magic using creatures, including people, are considered Mystics? I dont think this is really possible.
Let me know what you guys think on the subject, and whichever way you decide to rule, I would like to know your reasons for making the decision as, obviously, Flea is one of my favorite characters and I love everything about him/her.