Денис Сепетов

foreach ($posts as $post) {
    $comments_number = get_comments_number($post->ID);
    if ($comments_number == 0) {
        array_push($new_posts, $post);
    }
}

foreach ($posts as $post) {
    if (strpos($post->post_title, "МСК+0") === false) // <<<==== вот этот блок
        continue;

    $comments_number = get_comments_number($post->ID);
    if ($comments_number == 0) {
        array_push($new_posts, $post);
    }
}