I'm going to think on this before replying, however I'll point out the only time I was harassed via electronic communications incessantly by a liberal was over the fact that Margaret Sanger was indeed a eugenist who specifically targeted people of color. They really really really do not like to have that little tidbit exposed to the general public, perhaps they don't even believe it themselves because it aligns them, many self-professed 'progressives' where race is concerned, with racist eugenists and that's a bitter pill to swallow especially considering the race most affected by abortion still are blacks.
Unlike the slavery issues, this 'past digging' is relevant because abortions are still prevalent occurances in the black community and planned parenthood is still a powerful organizations in the U.S.