"Clyde", who somehow seemed to escape me while posting yesterday, is considered to have been the oldest Black Rhinoceros in captivity when he died. "Klyde" is most certainly not the oldest Black Rhinoceros in captivity currently.
However, what you said about how "Klyde" is likely never to see another female is true. He's genetically invaluable, and since the Black Rhinoceros is solitary, there is no reason for him to ever be introduced to a female again. That's why he was moved to the Cincinnati Zoo. Cincinnati decided to no longer actively breed Black Rhinoceroses and focus on breeding their Asian rhinoceros species. Columbus wanted to free up space in the Pachyderm Building to continue breeding Black Rhinoceroses. Since Klyde is genetically invaluable and Cincinnati still had the room to hold a single Black Rhinoceros, he was transferred to Cincinnati in 2009.
However, what you said about how "Klyde" is likely never to see another female is true. He's genetically invaluable, and since the Black Rhinoceros is solitary, there is no reason for him to ever be introduced to a female again. That's why he was moved to the Cincinnati Zoo. Cincinnati decided to no longer actively breed Black Rhinoceroses and focus on breeding their Asian rhinoceros species. Columbus wanted to free up space in the Pachyderm Building to continue breeding Black Rhinoceroses. Since Klyde is genetically invaluable and Cincinnati still had the room to hold a single Black Rhinoceros, he was transferred to Cincinnati in 2009.