It's possible to use the Sitemap without mod_rewrite by setting the Sitemap URL scheme to empty string. However this behaviour is not intiutive, not clearly documented and if you actually do it, the plugin status tells people to add RewriteRule ^$ to their .htaccess which of course is total mumpitz. So the plugin status has to be made aware of this case and the documentation should be improved.
It's possible to use the Sitemap without mod_rewrite by setting the Sitemap URL scheme to empty string. However this behaviour is not intiutive, not clearly documented and if you actually do it, the plugin status tells people to add RewriteRule ^$ to their .htaccess which of course is total mumpitz. So the plugin status has to be made aware of this case and the documentation should be improved.