It sounds as though your son is in a place where they are keeping a close eye on him, and that's great news, hummingbird! I know that you are worried, and it sounds like he will need ongoing help. I hope and pray that this will be the beginning of a new direction for him!
Only time will tell what may have happened to your son and when. You may never know. It may be something he or his therapist will never be able to discuss with you. It does sound, though, that things are moving forward.
Time takes time, I'm afraid. Please try to get some rest!