What is reported here doesn't actually solve the mystery. People in such a situation would not chose to leave the levers locked. They did so because they could not do otherwise.
They were already dead, so it didn't matter to them if the keel weight dropped or not.
I will have to search way back in my posting history to find that exchange. Perhaps the Freeper who told me what happened will see this thread and get involved in this discussion.
Did they die from the concussion of the blast, as someone in here suggested? Or perhaps knocked unconscious?
Years ago we rented a beach house on Sullivan Island. Sitting on the porch at night we could see a red buoy light slowly blinking offshore, far across the dark water, near where the Hunley was found. Later, I went to see the submarine, and there was a cutaway full sized model there. The bench for the crew was slanted downward and slightly above the 9:00 o’clock position in the rounded hull. This forced their hands downward on the cranks which came out almost to the edge of the bench with little room for their legs. Of course, the cranks were offset from one another to provide a continuous power stroke, but this made it almost impossible for the crew to extricate themselves once in place. If anything went wrong, there was no quick way out, except to die.
In support of that line of thought - In most unexpected/unplanned situation, even those with life or death consequences, the average person will spend the first second or two denying the event is taking place. Only after that will they think about the actions they should be taking, then followed by taking some form of action. That is why student pilots are drilled by their instructors so intensely on the subject of losing power on takeoff. At that very vulnerable point in a flight, there is close to zero time for thinking or reflection. The actions have to be both quick and correct, and I doubt that the Hunley crew had ever practiced an emergency surfacing drill. Becoming partially disabled by either the shock of the torpedo explosion, by the reversal of the control surfaces (since they were trying to back away from the Union ship), and/or any sticking release levers would have undone them.