His main three themes (author bias, statistical significance, double-blinding/scientific rigour/confounding) are not at all unique to research with psychedelics. If the author's point is that we should take all studies with a grain of salt then why focus on psychedelics? If psychedelics is really such a problem field then I would expect more evidence than a couple bad actors (the MAPS stuff sounds terrible!) and light issues in a few studies that were brought up in reviews before publication.
It seems the main point isn't research as much as the public's perception and hype (partially fueled by researchers to be fair). That's a good point and I'm totally against the psychedelics version of "weed cures cancer" bros. But, as the author points out, this isn't unique to psychedelics either! Ironically, I found the intro and most of the article to sound much more critical of the research than the conclusion really is.