Do you understand why BO has spent well over 1M to protect his any/all records that show what he claims?
Nope. Even if that is true (why would it cost so much money to protect things that aren't public records in the first place? Dunno) but even if it is, he'd be foolish to release a birth certificate now.
First of all, people would just claim it's a fraud anyway... and second... when he's got his opponents looking foolish with all their wailing and gnashing of teeth his best play is to let them keep doing it.