If they all escaped, and are in the water in the South Atlantic, there is a finite time before the cold has it lethal effects. That might answer why, for the moment, the crew might be biding their time in escaping?
@Marcantilian: are you aware of whether or not there is a buoy-borne ELT system equipped on the subs in Argentina for emergencies like this? (The idea being release the buoy, it goes to the surface and then transmits distress signals periodically using salt water battery, sending "last known location" and an alert ... etc ...)