Right now the Draftwriter does not have the right to publish articles but only to submit them for review.
That logic does not extend to categories though: A Draftwriter is able to create a category and set it public so it is visible in the Help Center.
The Draftwriter should be prevented from accidently publishing categories, e.g. by limiting him to creating them internally or by extending the article planner logic (submit for review) to categories.