The vast majority of psychologists are Liberal. 50% of psychological studies cannot be replicated. I have seen definitions of mental illness change like seasonal fashions in my life. Homosassa lit is now normal, but you have a "phobia" if you won't kiss a man in a wig.
If they -do- decide to ban gun owners in for the mentally ill, it should be a determination that is made by a neurologist, not a psychologist. This is the only thing I agree with Scientology about: psychology has been coopted and turned into a pseudoscience.