Thanks for the reply John. However for some reason the PDF generated by the ArcGIS server overrides the selection of "None."
For instance, changing the option to "None" and exporting directly from the *.mxd it works properly. As the PDF file has the toggle layer functionality gone.
But when exporting from the API (IE8) the toggle layer functionality still exists. Seems like a bug to me.
Any other suggestions would be appreciated. Thanks!