remove the noindex meta tag from single reply comment links

wp-comment-noreply-meta.php

<?php
add_action( 'init', 'rkv_comment_noindex_base' );
/**
 * remove the noindex flag on the reply links
 * when not using Yoast SEO
 *
 * @return null
 */
function rkv_comment_noindex_base() {

	if ( isset( $_GET['replytocom'] ) ) {
		remove_action( 'wp_head', 'wp_no_robots' );
	}
}

add_filter( 'wpseo_robots', 'rkv_comment_noindex_yoast' );
/**
 * remove the meta index tag for replyto
 * links when Yoast SEO is active
 *
 * @param  [string]    $robotsstr     the current string
 * @return null
 */
function rkv_comment_noindex_yoast( $robotsstr ) {

	// bail without Yoast
	if ( ! class_exists( 'WPSEO_Frontend' ) ) {
		return $robotsstr;
	}

	// bail without that query string
	if ( ! isset( $_GET['replytocom'] ) ) {
		return $robotsstr;
	}

	// return false to remove the tag
	return false;
}