Tho I can't speak for the poster, I got the impression that the goal here was to try to get some of the Christian right to vote "pragmatically" instead of on principles. By accepting late term abortions, he's taken minority position. By accepting it being a civil rights, federal issue, I think he's taking another minority position.
While I would love to see legal abortion beyond saving the life of the mother made illegal, I doubt that will become the law of the land during my lifetime, so for now, I'll take some incremental ism. After making most late term abortions illegal (life of mother exception), send the rest back to the states.
The reality is that in nearly all cases continuing the pregnancy puts the mother’s life at risk, the baby is almost certain to die anyway because it is generally an ectopic. This situation is very rare and nobody is suggesting that the mother not be operated on.
As far as rape/incest goes, statistics suggest that only about one to two percent of abortions are performed on women who conceived during rape or incest. However, in these cases, abortion is still not the answer. No CIVILIZED society has ever punished the child for the crimes of their father.