You seem confused about several things here. Unlike Biblical exegesis, in this conversation we are trying to elaborate and discuss possibilities for the cultural features of a world that was only loosely sketched out. You realize this is a fictional world we're discussing, not a statement of morality, or a manifesto that would require "backpedaling"?
The point of introducing socially acceptable non-consensual sex was to demonstrate huge cultural differences. Neither EY nor anyone else is claiming this would be a good thing, or "benign" : it's just a demonstration of cultural change over time.
Someone in the future, unless he was a historian, might not be familiar with history books discussing 20th century life. He might think lots of rape in the 20th century would be good (incorrectly) because non-consensual sex is a good thing by his cultural standards. He'd be wrong, but he wouldn't realize it.
Your question is analogous to "I don't see why someone now couldn't see that slavery was a good thing back in the 17th century, given that he'd have historical knowledge of what that society was like." Well, yes, slavery was seen (by some people) as a good thing back then, but it's not now. In the story, non-consensual sex is seen (incorrectly) as a good thing in the future, so people in the future interpret the past through those biases.
As promised, here is the "Q" part of the Less Wrong Video Q&A with Eliezer Yudkowsky.
The Rules
1) One question per comment (to allow voting to carry more information about people's preferences).
2) Try to be as clear and concise as possible. If your question can't be condensed to a few paragraphs, you should probably ask in a separate post. Make sure you have an actual question somewhere in there (you can bold it to make it easier to scan).
3) Eliezer hasn't been subpoenaed. He will simply ignore the questions he doesn't want to answer, even if they somehow received 3^^^3 votes.
4) If you reference certain things that are online in your question, provide a link.
5) This thread will be open to questions and votes for at least 7 days. After that, it is up to Eliezer to decide when the best time to film his answers will be. [Update: Today, November 18, marks the 7th day since this thread was posted. If you haven't already done so, now would be a good time to review the questions and vote for your favorites.]
Suggestions
Don't limit yourself to things that have been mentioned on OB/LW. I expect that this will be the majority of questions, but you shouldn't feel limited to these topics. I've always found that a wide variety of topics makes a Q&A more interesting. If you're uncertain, ask anyway and let the voting sort out the wheat from the chaff.
It's okay to attempt humor (but good luck, it's a tough crowd).
If a discussion breaks out about a question (f.ex. to ask for clarifications) and the original poster decides to modify the question, the top level comment should be updated with the modified question (make it easy to find your question, don't have the latest version buried in a long thread).
Update: Eliezer's video answers to 30 questions from this thread can be found here.