Well, that's not entirely true. Although some of the drafts held at UCLA do not credit the author, the collection there does include Ellison's two drafts of the story outline and three drafts of the teleplay, as well as the re-written teleplay by Steven Corabatsos which Ellison hated.
Who knows what else the Roddenberry estate has that it hasn't released to the public. The Justman memo, for example, isn't in the UCLA collection.
Fascinating! It's hard to believe that such material would survive, but it would seem so and I certainly have no reason to doubt you. However, I will stick to my position that no one at this point and time can be trusted to be telling the whole "truth". As I mentioned there has to be a Rashoman type of effect at work after all these years. TV script writing is an inherently messy process and sorting out which is the hero or the victim in the eternal pissing match between Ellison and GR strikes me as an amusing, but ultimately futile exercise.