This message is from november 1939. The Laconia incident and the following order was from 1942. Some time warping here?
This is the Laconia order 1942:
"1. All efforts to save survivors of sunken ships, such as the fishing out of swimming men and putting them on board lifeboats, the righting of overturned lifeboats, or the handing over of food and water, must stop. Rescue contradicts the most basic demands of the war: the destruction of hostile ships and their crews.
2. The orders concerning the bringing-in of skippers and chief engineers stay in effect.
3. Survivors are to be saved only if their statements are important for the boat.
4. Stay firm. Remember that the enemy has no regard for women and children when bombing German cities!"
AFAIK the above 1939 order was given because many commanders offered help to the torpedoed sailors. In some cases they were in dangerous situations while doing this (caught by a plane or escort ship). As a part of the unrestricted u-boat warfare no one should be rescued. Sailors are the same important "war material" like ships, tanks, planes, ammo and so on.
This text is not exhaustive, i´ve to re-check my books