All it takes is proving it once in court, what is he so afraid of?
What is it in his original birth certificate that is so embarrassing he can not show it?
My are some people naive. You do realize that the birth certificate claims account for only about half the lawsuits. If he allows any of them to go to trial, he admits the plaintiff's have standing, which means he'll then be tied up in endless litigation as suit after suit will continue to be brought.
That's why the correct response to a frivolous lawsuit is a motion to dimsmiss on basis of standing. Doing anything else is an invitation to spending a lifetime in court.
what is he so afraid of?
Nothing. He just doesn't want the hassle of having to defend against twenty different simultaneous lawsuits at once. I can't say I blame him.