This may be old news.. but here's the link. How people think Carter's an upstanding guy is beyond me.
http://www.cnn.com/2007/US/01/11/carter.resignations/index.html
I just wasted time reading twice the article you linked. In it there is no reference to the sentence which is the subject of the Post editorial.
What is news to me ... and I do pay attention ... is that Carter is unequivocally saying that terror is okay as long as it stops once the terrorists get what they want.
The professionals at the Post consider that sentence news ... not the book itself, not Jimmy Carter's well known antipathy to Israel but that particular sentence.