Ummm...technically Riku and DiZ aren't the only ones with the Superior's scent. Riku didn't meet EM, but by the fact that the princesses sensed twilight coming from EM, I would take a guess that he would have the same scent as the Superior(if he isn't the Superior himself, that is). Oh, and I agree that Riku isn't with the Org. Actually I agree with nothing because there are scenes and other tidbits of info that reject both sides. For those who think that Riku is in the Org.:
He couldn't have joined for any reason at all(spying or to actually join) because he just came from killing/defeating members of teh damn group he would join! And I don't care what you think, but I don't think that those deaths/defeats(for those who think they're alive) went unnoticed. And for those who think they're alive, that's even more reason to believe that he isn't apart of the Org., because they would've reported what happened to at least #1 if not the Superior. Riku(and Mickey) wouldn't have been able to get close to joining. The only way they would be able to join is if the Superior knew and made it a trap. But then I don't think Riku would be stupid enough to join. And if not him, then definitely Mickey would've known it was a trap.
And then for those who think that Riku is NOT a member of the Org.:
Riku may be that unknown in the picture. And if it is, then what other reason would he be able to control the Nobodies like that(if they need controlling that is.....they do have souls)?But wait! There may be a reason. It's been a year. Most likely Riku has become more defined as twilight then in CoM, so why would the Nobodies attack something that would basically be just like them?(I'm guessing at this, but the Dusks at least have no eyes. So what else would they use to sense what they are attacking. I'm guessing that they sniff the force just like Riku was able to in CoM). So of course they would stay at bay if he told them too. He would have the same scent signature as them.
Oops. I just realized. I just basically chose a side. Oh well.