I created a content only page type page (under a regular form based site) and is able to see the compare for content only page type.
Are you not seeing it using Preview? If so, that's because there is no "page" to view in the admin UI by default, but you can add URL pattern to display the preview for MVC.
The preview of the selected page is not available. Verify that the given page type has a valid 'URL pattern' specified in the Page types application.