Well no just the panic means they are more active and expend energy much faster. Just think of yourself in that situation and how much energy you'd spend dealing with the cold and trying to find a boat. That's not even to mention what they were witnessing as the ship went down.I always thought of hypothermia as more of a physical thing than a psychological thing. You're implying that people in the water died at least partially due to psychological shock.
What is your source for this?
And no source just the only rational explanation since on paper alcohol is supposed to make you freeze faster. He's the only one out of over 1000 people to make it(or even come close, just think there were like 10 people tops still alive in the water after around a half hour), and he was under considerably less duress than say Harold Bride and the people who survived the night on the collapsible with only exposure to the water not being close to entirely submerged.