> I don't know if the author of this post had any medical credentials.

In his defense, this is written on his personal blog where (quite possibly) many readers already have some reason to trust his advice. And while I'm not sure what counts as appropriate credentials, on his linked HN bio (https://news.ycombinator.com/user?id=bookofjoe) he claims to be a "Retired (38 years in practice) neurosurgical anesthesiologist". He also links to a lot of Google Scholar papers on medical topics for which he is a co-author.

(Oops, beaten by Dan, but I'll leave it up anyway. While I agree with Dan that you might have phrased it a bit better, I did think it was a fair question.)