The trouble with the Costa story is it's tumbling out piecemeal and very generalised headlines are being quickly drawn as a result. It's like taking a town of 4,500 people and saying because x happened in somebody's front room, y must be true in every house. Only the IMO investigation is going to get close to the whole story.
There were obviously huge institutional shortcomings. Although they hadn't done an evac drill, telling people to go back to their cabins may have been a not bad stab at crowd control on someone's part. Had they done an evac drill, the instruction is go back to your cabin, dress warmly, pick up any medication, put on your life jacket and go to your muster station.
^^ Once there, Ankou, you have to take your chances. Tell mrs kou not to jump though, the safest (ie least worse) place is still on the ship; you stay as dry as you can as long as you can.