So my physics background wonders whether the weight and/or weight distribution of the broken PRS is (was) different from the typical models he plays, which (seemingly) don't break so easily. This guitar broke because the applied torques at the pivot point, generated by the Center of Mass of the neck and the CoM of the body dropping at the fulcrum point of the neck joint and his knee, was stronger than the material (wood). And apparently he has abused other models without such unfortunate consequences.
i.e. if the body was differently shaped, along with a different neck/headstock weight/design, maybe it wouldn't have applied such a great force - the CoMs might be closer to the fulcrum (so applied torques are lower), or the masses might be lower (also lowering torques).
Or maybe he just got unlucky with that piece of maple.