LP fuel jockeys are rarely well-versed in tank repair, so I wouldn't be too alarmed. As the others have said, it's not clear what an "automatic shutoff" is either, since that is not a standard technical term for LP tanks and that alone makes the advice suspect.
Your tank does have an overfill protection device (OPD) inside the tank which could be termed an "auto shutoff" from the perspective of filling the tank, but it would take some thorough testing to know if it was bad. That would be a rare failure in any case. Replacement, if needed, is best done by a trained LP professional at an LP gas shop (not an RV dealer). The OPD stops the filling process at approximately the 80% level, which is the "safe" fill point mandated by the National Fire Code (NFP). It is not exact, though.
Dan mentioned the overflow port. Standard practice is to open the overflow port and pump LP into the tank via the big filler port until liquid LP begins to bubble out of the overflow. Then close the overflow port. The OPD device may or may not auto-close the filler port before that happens, but usually not.
If the fuel jockey was relying on the OPD to stop the fill process, he may have concluded it wasn't working if LP bubbled out of the overflow. That's an erroneous conclusion.