I don’t follow Mathews, but I’m guessing the trigger for his response was a WaPo article linking Conservatives to the pro-slavery activists of the 1800s.

From the article

Not all these figures identify as right-wing. They typically dislike President Trump but say they’re being pushed rightward — or driven to defend the rights of conservatives — by intolerance and extremism on the left. The reasonable right includes people like Shapiro and the radio commentator Dave Rubin; legal scholar Amy Wax and Jordan Peterson, the Canadian academic who warns about identity politics; the social psychologist Jonathan Haidt; the New York Times columnist Bari Weiss and the American Enterprise Institute scholar Christina Hoff Sommers, self-described feminists who decry excesses in the feminist movement; the novelist Bret Easton Ellis and the podcaster Sam Harris, who believe that important subjects have needlessly been excluded from political discussions. They present their concerns as, principally, freedom of speech and diversity of thought. Weiss has called them “renegade” ideological explorers who venture into “dangerous” territory despite the “outrage and derision” directed their way by haughty social gatekeepers.

So it felt frustrating: When I read Weiss, when I listened to Shapiro, when I watched Peterson or read the supposedly heterodox online magazine Quillette, what was I reminded of? 

My childhood home is just a half-hour drive from the Manassas battlefield in Virginia, and I grew up intensely fascinated by the Civil War. I loved perusing soldiers’ diaries. During my senior year in college, I studied almost nothing but Abraham Lincoln’s speeches. As I wrote my thesis on a key Lincoln address, Civil War rhetoric was almost all I read: not just that of the 16th president but also that of his adversaries.

Thinking back on those debates, I finally figured it out. The reasonable right’s rhetoric is exactly the same as the antebellum rhetoric I’d read so much of. The same exact words. The same exact arguments. Rhetoric, to be precise, in support of the slave-owning South.

And

It might sound strange that America’s proslavery faction styled itself the guardian of freedom and minority rights. And yet it did. In a deep study of antebellum Southern rhetoric, Patricia Roberts-Miller, a professor of rhetoric at the University of Texas at Austin, characterizes the story that proslavery writers “wanted to tell” between the 1830s and 1860s as not one of “demanding more power, but of David resisting Goliath.”

https://www.washingtonpost.com/outlook/2019/08/29/conservatives-say-weve-abandoned-reason-civility-old-south-said-that-too/