Show the modified date except though it's never been modified

/* Show the modified date except though it's never been modified */
function jeg_get_post_date( $format = '', $post = null ) {
    $publish_date  = isset( $post->publish_date ) ? date( $format ?: 'Y-m-d', $post->publish_date ) : get_the_date( $format, $post );
    $modified_date = isset( $post->update_date ) ? date( $format ?: 'Y-m-d', $post->update_date ) : get_the_modified_date( $format, $post );
    $publish_date_number_format  = isset( $post->publish_date ) ? date( 'Y-m-d', $post->publish_date ) : get_the_date( 'Y-m-d', $post );
    $modified_date_number_format = isset( $post->update_date ) ? date( 'Y-m-d', $post->update_date ) : get_the_modified_date( 'Y-m-d', $post );

    if ( get_theme_mod( 'jnews_global_post_date', 'modified' ) === 'publish' ) {
        return $publish_date;
    } elseif ( get_theme_mod( 'jnews_global_post_date', 'modified' ) === 'both' ) {
        if ( count( wp_get_post_revisions( $post ) ) === 0 ) {
            return $publish_date;
        } else {
            return $publish_date . ' - ' . jnews_return_translation( 'Updated on', 'jnews', 'updated_on' ) . ' ' . $modified_date;
        }
    } elseif ( get_theme_mod( 'jnews_global_post_date', 'modified' ) === 'modified' ) {
        if ( strtotime( $publish_date_number_format ) >= strtotime( $modified_date_number_format ) ) {
            return $publish_date;
        } else {
            return $modified_date;
        }
    }

    return $publish_date;
}