Yep, Thats exactly right. I went back and took a quick looksee, I don't see any evidence that Kabuto cloned Sasuke or ever used his techniques.

There are now three ways for Oro to grab a Rinnegan 1) Take Obito'sMS pair from Obito and Kakashin (Maybe that would be enough given that he has Hashirama's clone body), or Madara's pair from Obito, Or Take Sasuke's EMS.