My guess is he found a dehumidstat and not a timer as an ex girlfriend's mother had electric baseboard heating and both bathrooms were on a central fan controlled by a dehumidstat in the main hallway.
If it was a timer it should have turned off the fan when it ran down and stayed off. With the zero to 100 markings for humidity I could see somebody confusing it with a timer.
The other question is why is the control located in a closet?
