> On the contrary, when someone is depressed, the immediate response by people around them is generally try to "cheer them up" or encourage them to exit that depressed state.

True, but that is when times are generally good. I doubt people would be "cheer up" in an actual disaster situation.

From what i understand depressed people generally do well in disaster situations because they can still focus on critical tasks without getting overwhelmed by all the other bad stuff going on that isn't an immediate problem. (Possibly that's just a popular conception from movies. No idea if its true)

It is from the movies. Depressed people in disaster situations dont act and frustrated their close ones by being additional burden. Disaster does not cure depression, the issue is still there, just with worst consequences.