--has a gluten problem that will magically disappear when they stop eating, but vigorously disagree that going gluten-free can be dangerous.

I don't know why anybody thinks we need wheat, brley, or rye to survive, but none of those grains have specific nutrients that we can't get from other sources, and no one HAS to have them in one's diet. So going gluten-free is a harmless thing to do, and one can see if it has any salutary effect on one's conditions. It may not make any difference, but it certainly won't make things worse. Except, of course, if one indeed does have problems with gluten and goes through temporary withdrawl symptoms, which have been reported occassionally (gluten can be addictive as it interacts with some of the brains opioid receptors, and some people get symptoms upon stopping it in the same way some people get sugar withdrawl symptoms).