I don't think the findings are all the flawed -- you see similar %'s in other developed economies. It's not like Lawrence Summers just extrapolated the data and relied only on that!
I edited my comment to say title and post. After reading a bit more thoroughly I realized he doesn't blindly use the graph data. But that title on the post is sure misleading! I guess the article title "A disaster is looming for American men" was a bit too vague for HN, but I think the replacement title is flawed.