It's all right, we know where you've been
Amazon's defense was that the two words are spelled similarly, and that their logs show that "adoption" is frequently a user's next search after "abortion", so the suggestion was automated, not ideological. Then, they retreated.
(The best news articles I've found on this were at BusinessWeek and The Independent. The best blog post, by which I mean the one which didn't either parrot the New York Times or engage in predictable ranting, is by Troy Brumley.)
There's a level on which this is reassuring to your Friendly Neighborhood Library-Man. One way of looking at this is as a reminder that computers simply cannot exercise human judgement. They need to be watched and maintained, interpreted and tweaked. (Further, it's a reminder that any algorithmic system can be gamed by human behavior, and sooner or later, a human will have to deal with it.) Someone with a mercenary mind might think of this as a modern John Henry story. Perhaps it's a little job security for us catalogers and reference librarians.
Then there's the more concerning level. Amazon had a perfectly valid, reasonable explanation for what was happening. Yet they backed down in the face of apparently one complaint. Why didn't they have faith in their tool? Why wouldn't they stand by their developers? Seeing how to improve the online shopping experience got Amazon where it is; I just can't see why they'd sell that out.
It's not like no one else has ever dealt with this before. Google, for example has a great page to explain potentially offensive search results. Wikipedia built a system to encourage editing toward neutral point of view. And of course, smart libraries have clear policies about renting meeting rooms or display space to community members. Even Amazon has some statements about proper behavior in its reviews and lists, and guides on its recommender system.
I'm afraid all I can think of is that this is one more reason not to trust big publicly-owned media companies. It's too easy to push them around. Amazon doesn't sell books anymore; their primary product is stock certificates, and we forget that at our peril. I can't quite connect the dots, but I'm positive that this was ultimately not about what was best for pro-life or pro-choice, but the price of AMZN.
Watching Amazon fold like this is just one more reason your local independent book or music seller deserves your commerce. (And if there's not one where you are, there are some great ones in DC and Portland I'll suggest for your online shopping convenience.) They may not have Amazon's pockets, but at least they're responsible to you, the customer.