Huh? 
I think they are impeccably clear about it:
"The S in the model name usually indicates that this is a set neck model, rather than a neck through, however some 4001S models were built as neck-through."
This is set neck, as the name S indicates, some others, however, are neck-thru even though they are also branded as S models.
The S does not stand for set-neck, never did, never will. His description is totally off-base.
