That said I do have a problem with silencing. This problem was solved in USENET with kill-lists, lists where each user can choose to ignore another list of users maintained democratically without resorting to a few mods, who can be benevolent or not. This is how we block spammy ip addresses using the hosts file! This is a solved problem with a simple solution, heck it can even be applied to every major social networking site out there.
On a side note, why can't HN code be made available on GitHub? It could be one of the biggest lisp projects overnight.