She says he's probably mentally ill. And she really hasn't followed the situation/news until recently, but that's the conclusion she came up with, hearing about his actions. Now I know some might see this as an excuse, but it could just be the truth -- how else could someone live such a bizarre, twisted life, attacking people he knew were telling the truth, destroying people's lives, etc., etc., unless he is a sociopath, or at least seriously bipolar/has some kind of major personality disorder.
Again, this does not excuse his repugnant behavior, but I think it is a plausible explanation. He might need help, seriously. And to be honest, he should seek it -- it might also be the only way people (some people) will understand his actions. If it is confirmed that he is disordered due to a mental illness (or multiple illnesses) some of this would almost make sense. Or at least make more sense.
If not, then what, he is just evil? Perhaps, but I think the odds of serious mental illness in this case are very, very high.