The author does in fact identify that left and far-left (and center and right) misinformation exists, but does not drive engagement. A cursory glance at the article reveals this.
I think your parent is quite aware of the contents of the article, and is questioning their ontology just like one would question a Jesuit's conception of 'heresy'.
The left is significantly more clever on how they move the Overton Window - doing it primarily by picking the topics that are discussed.
For example - the new focus on anti-Asian crime as a wedge issue.
Can you go into detail? Also, which country are you referring to?
Both sides pick topics that are discussed. Have you seen the news about migrants and the 'Biden Border Crisis' as I've seen it called?