To allow comments in scheduled posts you could hook in comment_on_draft action and copy the insert comment code from wp-comments-post.php inside the callback function:.
add_action( 'comment_on_draft', function( $comment_post_ID ) {
do_action( 'pre_comment_on_post', $comment_post_ID );
$comment_author = ( isset($_POST['author']) ) ? trim(strip_tags($_POST['author'])) : null;
$comment_author_email = ( isset($_POST['email']) ) ? trim($_POST['email']) : null;
$comment_author_url = ( isset($_POST['url']) ) ? trim($_POST['url']) : null;
$comment_content = ( isset($_POST['comment']) ) ? trim($_POST['comment']) : null;
// If the user is logged in
$user = wp_get_current_user();
if ( $user->exists() ) {
if ( empty( $user->display_name ) )
$user->display_name=$user->user_login;
$comment_author = wp_slash( $user->display_name );
$comment_author_email = wp_slash( $user->user_email );
$comment_author_url = wp_slash( $user->user_url );
if ( current_user_can( 'unfiltered_html' ) ) {
if ( ! isset( $_POST['_wp_unfiltered_html_comment'] )
|| ! wp_verify_nonce( $_POST['_wp_unfiltered_html_comment'], 'unfiltered-html-comment_' . $comment_post_ID )
) {
kses_remove_filters(); // start with a clean slate
kses_init_filters(); // set up the filters
}
}
} else {
if ( get_option( 'comment_registration' ) || 'private' == $status ) {
wp_die( __( 'Sorry, you must be logged in to post a comment.' ), 403 );
}
}
$comment_type = '';
if ( get_option('require_name_email') && !$user->exists() ) {
if ( 6 > strlen( $comment_author_email ) || '' == $comment_author ) {
wp_die( __( '<strong>ERROR</strong>: please fill the required fields (name, email).' ), 200 );
} else if ( ! is_email( $comment_author_email ) ) {
wp_die( __( '<strong>ERROR</strong>: please enter a valid email address.' ), 200 );
}
}
if ( '' == $comment_content ) {
wp_die( __( '<strong>ERROR</strong>: please type a comment.' ), 200 );
}
$comment_parent = isset($_POST['comment_parent']) ? absint($_POST['comment_parent']) : 0;
$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type', 'comment_parent', 'user_ID');
$comment_id = wp_new_comment( $commentdata );
if ( ! $comment_id ) {
wp_die( __( "<strong>ERROR</strong>: The comment could not be saved. Please try again later." ) );
}
$comment = get_comment( $comment_id );
/**
* Perform other actions when comment cookies are set.
*
* @since 3.4.0
*
* @param object $comment Comment object.
* @param WP_User $user User object. The user may not exist.
*/
do_action( 'set_comment_cookies', $comment, $user );
$location = empty($_POST['redirect_to']) ? get_comment_link($comment_id) : $_POST['redirect_to'] . '#comment-' . $comment_id;
/**
* Filter the location URI to send the commenter after posting.
*
* @since 2.0.5
*
* @param string $location The 'redirect_to' URI sent via $_POST.
* @param object $comment Comment object.
*/
$location = apply_filters( 'comment_post_redirect', $location, $comment );
wp_safe_redirect( $location );
exit;
});
Additionally, we could check for "future" status to exclude "draft" posts, but in this case we can end up with conflicts with other plugins that use comment_on_draft action hook:
add_action( 'comment_on_draft', function( $comment_post_ID ) {
if( get_post_status( $comment_post_ID ) != 'future' ) {
exit;
}
//Rest of the code
});