It seems like there are some more subtle ways of doing it though. If Dave had a mechanism for proving to HN that he was the owner of a particular URL (e.g. by adding something to its html), then perhaps he could tell HN what to do with that url: Don't allow links to it at all; Link, but don't have a comment thread, etc.

Come to think of it, if it was successful this could be generalized to a mechanism that all forums could be expected to support, just like search engines are supposed to honor robots.txt