I'm pretty sure that Jon basically doesn't release this due to the current state of the band and, moreover, himself. Contrast to what some delusional fans think and to what he says in interviews "I'm feeling great vocally", he knows how bad he sounds. Just think back to Mohegan Sun 2011 when he failed to hit the "this is my hometown" in Wild In The Streets and then shook his head in disgust aboout himself. He knows very well that if he released old material and casual fans would pick it up, the backfire would be horrendous. Let's face, we know how the current state is, but a casual just might pick up that release, think "that's good, I'll check them out live" and then be absolutely shocked about it. He won't risk that since the casuals are by far still the main part of a concert audience.
I pretty much think that his "no nostalgia/not living in the past" attitude is primarily in order to turn these discussions down from the get-go. The only chance we'll have of getting these kind of things is when the band is retired for good.