Editors and authors share the creative "ownership" of an article. Here, they did actually come up with a somewhat satisfying compromise (the note), although punting the difficult decisions to the reader is somewhat cheap.
FWIW I probably agree more with the editor than the author. Yet I found their note rather obnoxious, and the author missed an easy chance to score a point for his "side".
The final decision not to publish an article including the disagreement was the author's. It was him who wanted only his side in the article, not the editor. So I don't quite see the scandal he makes out.
(In any case, it's insane how people are unable to entertain the theory that Assange is both an important and positive figure in the fight for privacy, as well as a creepy misogynist with the sort if psychological issues required for that self-imposed martyrdom in the embassy.)