Yes, I would be 100% satisfied that they are authentic. All he has to do is direct the IRS to release them so they wouldn't come from him anyway.
I get your point, I think you are missing mine though, which is that you have not adequately considered the consequences of this. So great, Obama releases his extra super duper long form birth certificate. He's an open book! Now conservatives want to see his tax returns - which is fine, he's an open book! Conservatives then say well what about your other banking records? Where's your checking account statement? Maybe from there they uncover that Obama signed up for a porn site or something and now that's a big national scandal. (and you know it would have been)
No one... absolutely no one is so squeaky clean that given enough time and resources dishonest and disreputable people won't be able to find something in your background to blow into some scandal or controversy. Every president should ask themselves if a records request is 1) made in good faith and 2) pertinent to your ability to do the job. Asking for Obama's birth certificate, while obviously borne out of racism, is in fact a valid question to ask. He answered it almost immediately with the standard of proof that's accepted all over the country. He ignored the later requests for a 'long form' certificate because they were both meaningless and made in bad faith. That's the right standard. Trump should release his tax returns because his financial interests directly relate to his ability to do the job. He's been dodging that for three years now. This isn't about Democrat or Republican, this is about basic good governance and the standard is the same for both parties.