He finally saw that your refutation of the original poster's error was in fact correct and he didn't want to admit it.
That's how I'm reading it, at least. I can't even think of a word to describe the error. It's as if I wrote that "home run output increased, coinciding with higher pitching velocities," and he thought that I was implying that pitchers are throwing the ball more slowly, causing more home runs.
I still don't see the point of narrowing the focus from long-term to short-term, though. No one is arguing that Smoot-Hawley caused the Great Depression.