Currently, Confluence does not allow user to search for pages/spaces created by deleted/disabled user using the username of the deleted/disabled user. User is only able to search pages/spaces created by delete/disabled user with the page titles. This will cause difficulties for the admin to keep track of the pages/spaces created by deleted/disabled user.
For Example:
Tim created a few pages in Confluence and the Confluence admin has deleted/disabled Tim's user account.
Mark is able to search the page created by Tim using the page title. However, when Mark tries to search the pages/spaces created by Tim with entering Tim's username in the contributor field in the search filter. The search result will not return pages created by Tim.