I don't see any difference between this and Donald Trump saying "You're fake news" to CNN reporters and refusing to answer.
1) CNN isn't a propaganda mouthpiece spreading misinformation. Now if Jagmeet refused answers from the National Post, I could see your point.
2) What was the question, whatever it was got lost in the 'you're never gonna be prime minister and you act like a child'. If they want to be taken seriously, they need to act seriously.