myCRED: Change post author on purchase

/**
 * Change Post Ownership
 * Changes the post author to the user who purchased the post using
 * the myCRED Sell Content add-on.
 * @requires myCRED 1.4 or higher
 * @version 1.1
 */
add_filter( 'mycred_add', 'change_post_ownership_on_content_purchase', 2, 3 );
function change_post_ownership_on_content_purchase( $reply, $request, $mycred ) {

    // Make sure we hook in when someone purchases content
    if ( $request['ref'] != 'buy_content' ) return $reply;

    // Make sure this is not the author payout (if used)
    if ( !isset( $request['data']['seller'] ) ) return $reply;

    // Start by getting the post from the reference id
    $post = get_post( (int) $request['ref_id'] );

    // Make sure the post still exist
    if ( isset( $post->post_author ) && $post->post_author != $request['user_id'] ) {
        $new_post_args = array();
        // Supply ID to indicate that this is an update
        $new_post_args['ID'] = (int) $request['ref_id'];
        // Items required for post update
        $new_post_args['post_title'] = $post->post_title;
        $new_post_args['post_content'] = $post->post_content;
        $new_post_args['post_status'] = $post->post_status;
        $new_post_args['post_type'] = $post->post_type;
        // New author
        $new_post_args['post_author'] = $request['user_id'];
        // Update
        wp_insert_post( $new_post_args );
    }

    return $reply;

}