He was slapped first and then punched the student that slapped him. The school is a psychiatric therapy in nature and not a regular public school.
They left this off the title.
I get that when "students were kicking the staff members while they were 'trying to control one of the students,'" tensions get high pretty quick.
However, one student slapping an instructor, at least somewhat separate from the other conflict, does not warrant the instructor punching that student in the face. "Punching in the face" is not a "restraint technique," and from the contents of this short article, there is no indication that the instructor was in fear of their safety or the safety of others based on that slap.
Most of the adolescents and children in the Provo Canyon School have been sent by their parents there not prisoners and this man had no right to assault them and their parents have no right to falsely imprison them.
If your child or adolescent in your care is mentally, get a doctor and get a fucking court order for involuntry pyschricratic care. There is due process for a reason to defend all people's human rights.