It was faxed to ABC. If it was efaxed, then a copy resides in the computer that received it and it will be made public by someone.
It is really evidence and cops will eventually get it or a copy. It will in turn become a public record when investigation is concluded. Since the guy is dead, that should be soon. Need autopsies all around including of perp and then rule out possible accomplices (there may well be some but probably not). We will see it.
As far as “Manifesto’s” from crazy people. I find them instructive for study. For example the Ted Kasinzki/Unibomer manifesto was well done and actually fascinating. He had a PhD from Michigan and had a lot to say. Of course PC damns you for even thinking like that. But they can GTH and Trump/Cruz will be the first to insist on it!