You are all trying to overthink this situation.  A Baggage car in a passenger train goes B/O in route and must be set out.  The Railroad will arrange to transfer the cargo if any to the quickest means possible to get to destination.  Most all railroads had had highway equipped carman crews that could be sent anywhere on the division to repair the car including changing out complete wheel sets and after repairs were made car would be picked up by a local freight and headed back to ware ever car was needed.  They did not stop a scheduled passenger train to pick up an empty car.

Paul C. Koehler