The point of sitemap.xml is to let Search Engines be able to index your whole site, including the pages that are not found crawling the normal content and menus. Excluding pages without a MenuTitle would defeat the whole purpose of sitemap.xml.
http://www.sitemaps.org/
"Web crawlers usually discover pages from links within the site and from other sites. Sitemaps supplement this data to allow crawlers that support Sitemaps to pick up all URLs in the Sitemap..."
http://www.sitemaps.org/
"Web crawlers usually discover pages from links within the site and from other sites. Sitemaps supplement this data to allow crawlers that support Sitemaps to pick up all URLs in the Sitemap..."