If that is the case, then the head end of the train has passed the semaphore in the stop position, and either the operator handed something up to the head end crew and should still be outside the depot watching the train by (rules required this on most railroads) and waiting to hand up a copy to the rear end, or else the signal has been ignored completely.
Usually such signals were not restored to the "stop" position by by the operator until the markers of the passing train had cleared the station. Not knowing anything about the operations on this particular railroad at the time I wouldn't hazard a guess as to what the situation actually was.
Interesting photo nonetheless....