Remember that you did ask for suggestions!
In the "other" thread, PLCProf proposed a touch-sensor detector or something like that to momentarily activate the relay whenever someone hand touched the control knob. That would involve some circuitry so I guess it was voted off the island. But remember the QSI motion sensor for the cattle-car sound cars? It was a simple but ingenious idea to detect motion.
If something like that could be attached to the shaft or any moving part of the rotary switch, it could trigger a timer (homebrew 555 or a $1-2 eBay module ) which would momentarily drive the new relay to remove track power from the passive-TIU.
It would be a simple job since I am indeed imagining you doing it. 
