That's why I didn't vote for that option myself. People keep asking about it though. One option would be to let users flag content as not appropriate for HN, and then have a per user option of filtering away content the community doesn't find appropriate.
I'm all for flagging the content. It'd be especially nice if it'd throw up a warning in front of the summary if enough people flag it.
Digg does pretty well in this regard. If enough people bury the story as inaccurate, you see a big "Warning! The contents of this article may be inaccurate!". That plus scanning a few comments are helpful for deciding not to waste my time on an article.
Suggested flags include: 'inaccurate', 'nsfw', 'not suitable for HN', etc.