Please read post 191. BO citizenship status is lot more complicated than where he was born.
According to some legal theories. But, IMHO, if he was a natural born citizen, and never renounced it himself as a legal adult, then he *is* a natural born US Citizen, regardless of the fact that other nations may have or may still claim him as one of theirs. It's US laws and its Constitution that count, not those of other nations.
So yes, it's still possible that he renounced it at some point, possibly by traveling on a passport from Indonesia or even Kenya, but it's a long shot.