A draft of McCann's original proposal would allow psychologists, nurses and counselors to enter a person into the national background check system, prohibiting that individual from legally possessing a firearm for a year.
Not qualified to diagnose anything. This could easily be used for personal vindictive purposes, setting aside all the other issues.
Likewise, everyone in health care has had problematic patients. A personality incompatibility isn't sufficient for a diagnosis, despite what many in the health fields think.