You didn't say
Acute Stress Disorder you said "mental breakdown". Funny thing though,
Acute Stress Disorder tends to be a temporary problem. So, if some one has suffered from this at some point in their life as a result of some trama, they get treatment and are able to work through it and are healed, should they be denied the right to arm themselves for the rest of their life?
You're just scapegoating at this point, why should any of us take you seriously?