I think he speaks of pre-Jinchuriki Rikudo. Rikudo freed the world from Juubi by sealing it away but didn't explicitly kill it. Well, Madara said something like Obito became like the Rikudo Sennin after becoming the Juubi's Jinchuriki.
I think it' clear that a Rikudo Sennin w/ a complete Juubi inside him stomps Obito.
He created the moon on his deathbed, but probably used Juubi's Chakra. Who knows. Unfortunately, no proper intel on that matter.
If he refers to Pre Jin Rikudo, then it depends.
-If he got Rinnegan before becoming the Juubi's Jin (I doubt it) Then he still destroys Obito.
-If he didn't, then I wouldn't know since his abilities are pretty much unknown.
I don't see how he could have used its chakra if he had already made them into the Bijuu. IIRC this is how it went.
Unseals Juubi---> Splits Chakra from its body and makes the 9 Bijuu ---> Seals the body away inside Chibaku Tensei, which became the moon.