You don’t need a “novel” or “kulah” -if something is mutar, it is mutar even if you have a beard and pe’os, and if it is asur, it is asur even if you keep your kippah srugah in your pocket. About the only haskafa differences are that some Dati Leumi who hold that anything that helps the Israeli army (e.g. driving an officer to the beach so he can relax with his family and Shabbos, and thereby be more rested on Sunday) is mutar, but that’s a minority. Anything life threatening takes priority over Shabbos, and always has. No hiddushim involved.
Whether someone wants a job that forces them to work on Shabbos, is a different matter. The frummer you are, the more likely you’ll skip the higher parnassah that a job that requires working on Shabbos commands (e.g. be a math teacher rather than a cryptographer for the NSA).
National security work can easily lead to situation where it becomes necessary to work on Shabbos since it becomes life saving (consider the lessons learned from the cryptographers who were piously waiting until Monday to decode the messages indicating that the Japanese Navy was bombing Pearl Harbor on Sunday morning).