The Last Updater filtering option is ideal for KB groups where most authors are submitting activation requests, as opposed to authors activating documents themselves. By selecting the LastUpdater column display, you may display the Username (e.g. the NetId + domain name)of the last person to update that document.
Some KB groups employ a workflow where most of their authors are submitting Document Activation Requests once the authors are ready to publish a document (as they do not have permissions to update themselves). The image below shows the In Review queue of a KB Admin who has two documents that an author in their group has updated who is requesting that the KB Admin approves of the content they added and as a result, Publish the document.
You may notice that the "Updated" information in the Document Information Table at the bottom of documents in the KB Admin Tools displays the name of the person who last touched the document, i.e. the person who activated the changes, and not necessarily the person who changed the document content.
By enabling the "LastUpdater" checkbox (found below the search filters in all Document Queues) this column will display the fully qualified username of the person who last edited the content (based on the Revision History), even if that person is no longer an active user. In the image below, you will see the LastUpdater display checkbox enabled in the Active Documents queue. As a result, the last column in the subsequent table displays the name of the last person to update a document.