I dunno, John - I didn't give an "informed" answer because your answer is correct. It's kinda like embedding an outside document in a web page, like I did for our church schedule the schedule is at one site (that I can edit), and the church Website is another one that I can't edit without requesting changes through the Webmaster.
In this case, Google controls the changes to the ads, and the ad texts don't show up when you do a "view source" for the Mudcat Forum Menu.

-Joe-