Did you read the article? He literally gave every example of maliciousness as right wing and provided no examples of how the left is equally manipulated.
So, is there an "equal opportunity" rule now? Do all citations of evil, atrocity, and maliciousness require both a "right-wing" and "left-wing" example just for the sake of fairness?
Why? Because too often, each side tries to paint the other as the center of all evil. And people of both sides get really tired of being painted that way. They tune out very quickly when they run into something that paints them that way. So if you want both sides to hear you, you have to not shoot only at one side.