Durandal called the Phor, nicked their ship, and vanished into the night, right? Seven (I assume it was 7) years later the Phor posse returned and swiftly annihilated the Tau Ceti colony...
I'm surprised the humans didn't forsee this and bundle themselves back to Mars in cold storage: the Marathon was still operational, no? True, the Phor would most probably have followed them to Sol, much to the displeasure of the UESC, but I don't think heroic sacrifice like Durandal intended would have crossed their mind.
So why did they hang around to get killed? Perhaps this question is answered in the games, but I've only played Infity and my knowledge is patchy at best. Thoughts?