If a DMOZ listed domain is sold for whatever reason and the site is changed, there is a good possibility the domain will be removed from the category it is listed in if an editor catches it. Sites are listed in the directory based on category. If you put up a new site that is no longer suitable for that category, it may be removed.
If you remove the site and park the domain, DMOZ has an automated bot that will detect it and red flag the listing to be looked over again for possible deletion by an editor.