Attacking “whiteness” is just another way to strike at Christendom, whatever is left of it. That is why African-Americans, like Clarence Thomas, who support traditional values are labeled “white.”
Rhetorically speaking, the second half of Bongino’s maxim sounds clunky; I believe it should be “Leftists believe Conservatives are bad people.”
I think Leftists think conservatives are "stupid" people...the same way that high school kids think their parents and adults, in general, are stupid.