I think you're confusing legal restrictions with moral restrictions. If the fetus/unborn child is a human, deserving of legal protections, how it was conceived (rape/incest) would be irrelevant. If it is not a human deserving of legal protections, then I agree it is immoral to have an abortion for the reasons on the bottom, but since it's not deserving of legal protections, the woman's preference still stands.
Now if the pregnancy cannot make it to term you aren't having an abortion, you are facilitating the manner in which the pregnancy fails.