For an article that decries the lack of scientific research in this area it sure is eager to pull conclusions from anecdotes rather than remaining unsure. I mean, the article uncritically quotes someone as saying they stopped digesting their food because of a bad experience while meditating.
Honestly, it sounds like David is someone with depression and mild anxiety. If I'd abandoned as much of my life as he had to fruitlessly chase an experience which wasn't returning then I think the same might happen to me.
People get unwell for many reasons. I think it'd be pretty uncontroversial to say that the sort of people willing to go hardcore with meditation are probably more likely to be susceptible to these problems. In the absence of any alternative evidence I'll continue to think of horses not zebras when I hear hoofbeats.
That's not to say that there couldn't be an issue. Self guided CBT can be prone to misuse by practitioners but that's just a symptom of their underlying depression, not the fault of the CBT.