I was just looking at CodeCanyon. Have you done it? can you give me a little more detail on how it works?
They have quality standards that you must meet to get approved. Browse through http://support.envato.com/index.php?/Knowledgebase/List/Inde... to find out more.
I'm still not completely sure why HN does that to be honest, especially since the heuristic appears to be pretty random.