Comment 6 for bug 1535666

/etc/apparmor.d/tunables/xdg-user-dirs.d/site.local is for just that, local site settings and that is why nothing is set in there. To see what apparmor is using as the defaults, see /etc/apparmor.d/tunables/xdg-user-dirs. You are free to adjust /etc/apparmor.d/tunables/xdg-user-dirs (though beware, it is a Debian conffile), /etc/apparmor.d/tunables/xdg-user-dirs.d/site.local or any other file in /etc/apparmor.d/tunables/xdg-user-dirs.d.