Once again we need to keep the realities of what producing a show is like. Stuff like Justman's memo probably survived more or less as fluke. Certainly no one was thinking in C.Y.A. terms in case of future blowups. No one could have known that COTEOF would become a classic episode and that TOS would become such a classic series where every incident would analyzed and broken apart. Certainly even Ellison with his grudge holding and egomania, I'm sure had better things to do than to document his role in writing a script for a marginally successful (at the time) TV series. Any documentation that would definitively settle the matter had I'm sure long since gone down the nearest memory hole long before the matter became a topic of interest to Trek fandom. It is fascinating to me that with such an acclaimed script is one that no one can really show who did what to it. I also find it somewhat interesting that just about everyone involved ended up hating each other with differing "Rashoman" style versions of what happened.