I respectfully and strongly disagree.
The conclusions about Martin as a person I gather from the historical evidence in the article are "Martin clearly knows little about history and obviously wanted to engage a little bit in the 'Fremen mirage' [as the author, Devereaux, himself would put it], but he's also a blowhard overstating his own knowledge and authority."
That Martin is "irresponsible", and his story "harmful", etcetera. That's all entirely what the author puts forward on the last few paragraphs... And something he didn't do in the first article in the series, and in the few other essays by him I've read. He keeps it fairly neutral, and focused on the history.
You see, the charitable interpretation in this case would be "don't attribute to malice what can be attributed to incompetence". In most of Devereaux's essays that have become popular here, he sticks to that one with reasonable consistency, but he clearly made an exception this time.