I that case I was hanging from the roof rafters, which were essentially telephone-pole sized. I hung across the grain, as it were, and was up in the top of the loft (not too many in the shelter or I couldn't have done it). I will admit to being somewhat skeptical, but it worked out pretty well for me.
In the case of the following picture from AT in 2005 and my old HH Expedition it didn't work out so well.
I WAS afraid that the old-style shelter would come down, so I wound up doing the bivy trick and sleeping with my torso on the small blue pad below the hammock. I was plenty sore the next morning!