Her organization supported mandatory sterilization. Voluntary, if possible. Involuntarily, as necessary.
As far as abortion being too barbaric, please consider this quote from Eugenicist Sanger:
Many, perhaps, will think it idle to go farther in demonstrating the immorality of large families, but since there is still an abundance of proof at hand, it may be offered for the sake of those who find difficulty in adjusting old-fashioned ideas to the facts. The most merciful thing that the large family does to one of its infant members is to kill it.
Margaret Sanger, Woman and the New Race, (New York: Eugenics Press, 1920), chapter 5.
Okay, but that doesn’t mean that Magaret Sanger supported abortion as the method for her desires. The quote does not mention support for abortion per se. I can’t believe Jonah Goldberg is that sloppy a researcher not to come to the conclusion about Margaret Sanger he came up with.