It really annoys me that they try to interrupt him when he's just being honest, and his comment isn't a "oh my god, you're so amazing" one. Just because he isn't saying something positive about the act it doesn't mean he doesn't have the right to his opinion.

because he will only bring down other acts and is more negative than any of the other acts (unfair for public voting whose opinions are easily swayed) that said, he's right with his criticism but should be criticising his own acts rather than just prasing them for terrible performances.