Log out page accessible when user is logged-out

My solution was to do this:

function tml_logout_page_redirect() {
    if ( Theme_My_Login::is_tml_page( 'logout' ) && ! is_user_logged_in() ) {
        wp_redirect( home_url() );
        exit;
    }
}
add_action( 'wp', 'tml_logout_page_redirect' );

Note: hooking to template_redirect or init doesn’t work so I had to hook to wp instead.