My mind started to wander more to the fact that Franklin was partially responsible for bringing newspapers to America (his brother actually started it), and that Franklin was a BOOK PRINTER, hello... The answer has to be in there somewhere.
I was thinking of two possible things. 1) people in the book don't know a whole lot because of the way society is set up, but they would likely know of Ben Franklin, and would buy him as some kind of authority. If he is in to what the firemen do, then we can all just accept it. or 2) Since in reality he is a symbol of literacy,