If the student is at risk of suicide, there are times when they need to seek professional help away from school. He could be a danger to himself or others. I think you are making it black and white. "If the student wants to stay at school, let them." It is not as simple as that. Think about it from the other perspective. If he killed himself at school and they knew he had serious mental health issues, people would be way more up and arms. "The school did nothing!"