It’s not about bothering the politician. It’s a political attack, designed to score political points. And the thing about political attacks, especially cheap ones, is that the person you attack can try to turn it around and make you look dumb. Trudeau calculated that calling his attackers out for their cheap shots would hurt him more than it would help, and he was probably right, since mocking aesthetic qualities is generally socially acceptable when the target is male. Anderson calculated that defending herself, and in so doing making her attackers look sexist and stupid, was the best move in her position, and I suspect she was right.