LOL. I saw a blank too.
That was harsh though.
I'm sure his little arguments are well received in dorm room bull sessions, especially after a few beers.
I have a bad habit, which I am trying to correct, of responding in an impatient manner with people like him. I even went back before his "departure" and edited out a few of my harsher comments.
Bottom line is that he has practiced a little spiel that serves him well in some instances, but not so well (as you pointed out) when he is questioned by people with a broader range of experience.