Locking people up will do a lot...
It will stop them from harming themselves or others until they can get the help they need in a hospital.
Actually the onus is on you to prove relevance of something you submit. Now explain how the part you bolded grants exclusive definition of 'threat' to those discussed in the article instead of everyone.
The guy hacked his own arm off. He's a threat to himself. It's really that simple. It really feels like you're arguing just for the sake of it right now.