I understand what you're saying and I do kind of agree with you, but you have to keep in mind who she's talking about. Now I'm not saying the dude deserves to die, but Justin Bieber has become a complete asshat and the fact that she recognizes that is good. It's good that she understands that he's a bad person and she doesn't just obsess over him because she thinks he's cute. Now should she be saying she wants to kill him? No, not at all, that's a terrible thing for anyone to say. But it is good that she is able to recognize that he is a bad person. Now at this point if I were her parents I'd say something like, "Honey you shouldn't say you want to kill someone because killing is bad. You can say you don't like someone or that you think they're a bad person, but not that you want to kill them."
But that's just me.
But that's just me.