I think he is asking about the sleeve like "slot", not the tab.

Could a snack be stored there? I suspect it would need to be something long and slim. Maybe a Slim Jim? Any chance Randy "The Macho Man" Savage was in on the design / R&D process?

Maybe it was meant to store some type of defensive weapon? Of course I have also heard that trained spies can kill a man using only a pencil.
So, we are back to it being a pencil holder.