Yeah, he basically didn't have any tension in the drive chain. Here's another test done by a friend: 2000 miles into a self-contained cross-country tour, climbing the steepest grade, desperately shift to "gear zero". Result? 18 new drive-side spokes, thank you very much.

Fun fact: 'dork disk' does not appear as an entry in Sheldon Brown's Bicycle Glossary. See: 'spoke protector'.