Well there was a cop on duty at Robb Elementary school. He did nothing to prevent the perp from entering the building and killing anyone. The solution isn’t more cops in schools. It’s about putting dangerous people with mental illnesses in mental health facilities, and empowering local communities to deal with such issues, i.e., teachers, and old students, having guns, so that these mentally ill individuals don’t think they will be the only person with a gun in a school.
Of course, you are correct, but if you do not deal with dangerous mentally ill people frequently (as I do), you may not know that a) getting an order to commit someone not guilty of a crime is impossible, and b) there are no facilities.