American Renaissance is a white nationalist publication, the person you are replying to has no interest in the truth.
I think the practice of ad homineming your political enemies is harmful to anyone's political aims. It strengthens your hold over your base, but it makes it harder for you to grow the boundary beyond it.
And many white progressives do. Perhaps most. They just won't say it to your face.
I don't think drawing the distinction where you are is actually cordoning off the thing you hope to cordon off.
They believe in a fictional you who can stay.