Two cases of mentally ill people not having guns with which I am familiar.
In the 1950`s certain gentleman was observed to being going a little nuts by his neighbors, relatives and the townsfolk. They complained that this guy was acting weird and threatening people as they walked by. The cops knew who he was and promptly came by and disarmed him. The fellow was sent to the state mental hospital for observation. They later deemed him totally crazy. The local townspeople said, “Thank God they got him put away before he killed someone as he was a danger to everyone here.” I knew this guy personally and I can say that good thing the cops got him before he really did some damage.
Another case I know well. A local fellow was shot by accident in a hunting accident, accidental discharge of another person`s rifle as the local fellow sat down next to it, bumped it and it discharged, wounding him in the stomach. He was rushed to the hospital, healed and was released. Soon thereafter he went completely nuts, threatening to kill an attorney, his relatives, and the hunters. He was promptly arrested, disarmed by the local police and thrown into jail overnight for observation. They let him out with the legal sentence that an FBI agent would be assigned to watch him wherever he went. He was forbidden to ever own guns again and never to set foot back into the state. It worked; he never returned and the local cops in another state watch him all the time and know exactly where he is all the time and tell his family in timely reports.
Arrest first, disarm him, get him off the streets, ask questions later. It saves lives.
This is how it was done 50 years ago.
Did you know that we don’t just “deem” you crazy under our constitution. You get DUE PROCESS. Let me tell you what that actually is. You get notice of the charge against you and the penalty or intended deprivation of rights intended. You get an attorney . You get a trial by jury unless you waive it. You get to defend yourself by presenting your witnesses and cross examining theirs. We don’t DEEM people crazy and take their rights or their property. Have we lost our minds?
Due process is involved in all of that. If the President meant that the police should be authorized to disarm an individual when he's detained, not at the end of court proceedings, that's what happens now. He should clarify that.