I see. You said above that a comment only has a day to make it out of pending. Why not auto-delete it when it doesn't? Edit: Never mind that question. Based on https://news.ycombinator.com/item?id=7446005 this seems to be the case (i.e., you won't have to delete a failed pending comment manually).

On a related note, the new system may prevent people from posting in the feature suggestion thread (https://news.ycombinator.com/item?id=363). Since it's already a special thread that never closes for comments perhaps comments posted there should not be made pending.