Patients gonna do what patients gonna do; the doctor's role is to advise and treat, not control the patient's life. Doesn't mean patient has a good idea, though.

I take the context of these warning comments to be a hypothetical patient who may not have been planning to fast on their own, but having read this paper, now wants to try it--i.e. a patient who may be tempted to treat this paper as medical advice. I think it's valid to point out that a single research paper does not necessarily constitute sound medical advice.