Setting the readonly flag when initializing the db connection does not stop inserting:
...
$config['readonly'] = true;
$clickHouse = new ClickHouseDB\Client($config);
$clickHouse->database($config['name']);
$clickHouse->setTimeout(10);
$clickHouse->setConnectTimeOut(5);
$clickHouse->ping(true);
$clickHouse->insert($table, $entries, $columns); // this is not supposed to work but it does