always lost interest in the explanations of this before they got to their point
so I read a historical footnote today about Roland
it said that Roland died in a rear-guard fight against the enemy. He could have sent for help to Charlemagne but this would probably have meant the king's death too, so Roland sacrificed himself
So... the Marathon (Roland) gets in trouble, but doesn't send for help or flee to Earth (Charlemagne) because that would mean the doom of the homeworld too. Durandal/AI is the only weapon the humans really have against the Phor, being out-teched in everything else. Durandal being Roland's sword of course.
So is that the explanation that i've been to lazy to read all these years?