If the subject of the article is notable, but the existing page consists primarily of attacks against the subject of the article, and there's no good revision to revert to, then the attack page should be deleted and an appropriate stub article should be written in its place. This is especially important if the page contains biographical material about a living person.
Attack pages eligible for speedy deletion may be inside or outside the main namespace. However, this policy is not usually meant to apply to requests for comment, requests for mediation, and similar processes (although these processes have their own guidelines for deletion of requests that are invalid or in bad faith). On the other hand, keeping a "list of enemies" or "list of everything bad user:XXX did" on your user space is neither constructive nor appropriate. Bear in mind that the key to resolving a dispute is not to find and list all the dirt you can find on somebody.