I'm diagnosed Schizoaffective disorder as well as ASD, when I was unwell I had this delusion around my bother being an alien and I threatened to harm him, I didn't know then but mental health professionals take that sort of thing very serious indeed, they will be making a very thorough risk assessment of your son and his needs which could possible get him moved into locked rehab or a low secure unit if he attempts harm towards any individual, They're are specialist units that cater for vulnerable people with ASD....