I did not say anything about his birth certificate, now did I?
Upon looking at your original statement, you are correct, you did not mention that you thought he wasn't a NBC, if that is the case then I am sorry for any hurt feelings. I took your meaning to be the opposite.
That said, where do you fall on the issue?
He's not natural born. That requires being born in the country of parents who are citizens.
He may or may not have been born in the country, but he definitely was not born of parents who were citizens, and does not even claim to have been. He also never claims to be "natural born", rather he claims to have been "native born", which he might be.