Don't give him too much credit. I see that as a typical progressive argument. Unable to argue from fact and reason, he's using the tools that he has. Citing sources is a waste of time because he won't accept as credible anything that doesn't support the progressive agenda. Once someone tires of going around progressive circles, he will claim victory. See it for what it is and it's a whole lot less intimidating. As I see it, he generally stops short of a personal attack, however. Don't get drawn into that.