*shrug* If the RPJs signed off on it, sure, just tread lightly and don't expect him to get the respect of an actual Master, and try to use him exclusively for providing opposition as you suggested. If you do decide to make him a proper PC, obviously he'd start at Apprentice.
Considering usage of this forum is not mandatory, what happens to "Denied" NPC's? As there is no requirement for submission in order to use an NPC does a denial really mean anything? For example if I create "Darth Uberness" to teach me "Forbidden skills blank through blank." or to serve as an overpowered combat assistant and it gets denied, what's to stop me from RPing with the same NPC that's been re-skinned and simply not put in the factory?
Honestly? Nothing. As a friend of mine is known to say, you can't fix stupid. Just as NPC creation is non-mandatory and non-binding, a denial would mean less than in other factory forums. Apart from really off-the-wall stuff, though, I can't imagine many cases when a denial would take place here. Fingers crossed.