You mentioned he's a "teddy bear". Is it possible that his sit bones are wider than the average guy's, and so instead of sitting on the suspended leather portion of his An-Atomica, he's sitting on the metal frame the leather is tacked to instead, or too close to the frame? (which would be VERY uncomfy on the sitz.) I think MimiTabby or someone said the An-Atomicas come in 3 different sizes. Maybe he just needs to switch for a wider size?
Somewhere there is a thread with a jillion very cool ideas for how to measure sit bones. (you just want to make sure his saddle is a good 1-2 cm wider on each side than he is, so 2-4 cm wider total to avoid the metal frame and to be sure he has wiggle room to shift positions)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson