Well there would obviously have to be some proof, in this day is shouldn’t be to hard for a victim to record something or have a text log ect…so let’s just say in legit situations where someone is acting nutty and there is proof of that but still haven’t committed a crime, they confiscate the gunsBut then someone could falsely accuse another to get the guns removed, rendering them vulnerable to a plot.
It's got to be thorough psychological/record vetting before gun purchase, and then a yearly evaluation to renew your license. It makes no sense to have loopholes that allow for removal of weapons by the state on vague assertions by another person.
If it were tough enough it would dissuade the average chump and those not responsible enough, and retain those with the discipline (and mental balance). If someone fails their re-evaluation, or doesn't show up, then the state can remove their weapons.