Jollyroger, you are experiencing Gulf States Toyota and their crappy way of doing business.
The person you spoke to was either lying to you or has no idea what he is talking about, or both, they are car salesmen.
Gulf States Toyota - this is the entity that buys/ships all the Toyotas in the southeast region of the country.
I have not seen one FJ Cruiser or 4Runner at a dealership with an OEM Toyota factory hitch. They are always equipped with aftermarket Reese style hitches. They have the same rating as the OEM hitch (5K lbs), and always sold on the window sticker as an "OEM" hitch, they are not. (I went through this same debacle when i bought my FJ and left their dealership a negative review for.) My guess as to why they do this is that they can make substantially more profit off selling the aftermarket hitch as "OEM" than they can selling the Toyota made one. The majority of folks out there buying will not know the difference, and that is what they are hoping for.
Since there are no changes to the 2013 i am aware of, everything from a previous year model should work.
Your only real options are:
Tell them you want them to remove the hitch since it is not OEM Toyota.
Show them what an OEM hitch and valance is and make them install it.
Buy it with it and replace it yourself with the correct one.
This is what the OEM hitch and valence should look like.
This is what the aftermarket versions look like. They hang down much further reducing departure angle and are heavier, more unsightly.