|The Survivalist is great to have on exploration missions. They can defend themselves more effectively against extra-terrestrial life forms and generally deal with these encounters better than anyone else.
Survivalist is handy mostly for the additional Alien Steak gains — your crew will appreciate the extra rations!
Most crews avoid possible instant death scenarios, so it tends to be rarely used for these, yet if you do encounter them (Mankarogs or Seismic Activity; Volcanoes kill everyone), you will be happy to have it. Beware, however, that it will increase the chances of death for the other explorers, including potential Diplomats.
A good skill for a Traitor, both for being taken along and for surviving the misfortune you cause.