He did not have to say it was true though (when parts of it were not, when it said she went to jail for example). He could have disguised it better and said it was based on a true story. He could have changed a lot more details about her. He could have not quoted directly.
As for her getting help - what kind of help do people suggest? Being nasty is not a MH condition. Being delusional is, but it is notoriously hard to treat. I used to work in psychiatric hospitals and there were people with extreme delusions we never managed to cure - the boy who thought his whole family were imposters who had kidnapped him comes to mind. And that was with the best treatment and medication available. Hallucinations, by contrast, are a snap to treat.
There are lots of people walking around who are delusional - conspiracy theorists, that relative with odd views, the slightly paranoid coworker. There are tons of people in the public eye who are convinced they are more intelligent/attractive/capable than they are and who would not be classed as mentally ill. You cant detain people on the chance they may do something in future. You cant force them to get treatment or accept they have a problem they don't accept. I think this woman is a good illustration of these real world difficulties.
I have to say that as much as I want people to speak their truth, in this case, I think what he has done is at odds with what he said he wanted to do.