I don't believe "rational" should be conflated with "ideal." Some people have pain inflicted upon them for longer and harder than their tolerance for pain allows. It is not irrational for those poor souls, if all other possible options have been exhausted, to consider and then execute suicide.

In my mind, the people who chose to jump out of windows of the Twin Towers, instead of being engulfed by rapidly encroaching flames, made the only rational choice available at the time.