I'm not sure where the author is seeing all these "fake Celiacs". I've heard of lots of celebs and such going gluten-free but can't name one that claims to be a Celiac without a diagnosis.
For a "scientist" this author doesn't seem to understand some basic principles, like that you can't disprove something by demanding evidence of it. A lot of people go gluten-free based on deductive (rather than objective) reasoning. "I feel better without gluten, ergo I should not eat it." Since there's no way to prove it objectively, you can't rule it out.
It seems any acutal points he may have had he totally voided in his comments.