Exactly. I read his response and said, "Wait, did I say anything about the far right?" No, I didn't.
In the US, right now violent extremists are almost all from the far right. At points in our history, we have had violent far-left extremists, so it's not impossible. It's not even inconceivable; given spiking wealth inequality, in some ways I'm surprised I haven't seen any anti-billionaire violence. Ditto climate-change and eco-terrorism. But it's definitely the case that extremist threats here are mostly from the right.
But I do think it's telling that he saw me pointing out the KKK and the American Nazi Party as examples of current violent extremism and thought, "How dare you attack the right!"