The HN code base is as much an experiment in Arc as it is a social news site. Also the feature set is surprisingly different (although I wish some of the features were here like comment collapsing and async comment submission).
Maybe it would be too much work to rewrite the specific logic that prevents HN 'manipulation' for reddit? Although I suppose much of the behavior and target audience is similar...
reddit.com/r/hackernews the new hacker news.
You might be joking, but in case not: reddit's code base is open source, so others can use it without moving the community under the reddit umbrella.