From a quote often attributed to George Orwell: "In a Time of Universal Deceit Telling the Truth Is a Revolutionary Act"
Peterson shows the Left the sum total of the content of their "message": Zero.
He is attacking them from his position as a well-respected rational thinker and authority on mental soundness.
When the Left realizes they have no defense against Peterson, they immediately collapse to ad hominem attacks.
Case in point, Peterson reduces Michael Eric Dyson in debate to where all Dyson has left is to accuse Peterson of being a "mean, mad white man."
Here is a brief clip of that exchange...C-SPAN Video Link.