The purpose of the article was to claim that the opinion of the only people legally allowed to make diagnoses is that the venn diagram shows the anti-authoritarians completely enclosed as a subset of the mentally ill folks.

The author's personal experience was being diagnosed with "issues with authority" because he didn't kiss up to his crazy boss. I don't see any conflict between not kissing up to his boss and owning firearms, so sure, let him go deer hunting on vacation if he's got no other, real, issues.