Vattel wrote a treatise. A treatise is a restatement of the laws. It is not controlling law anywhere and never has been. Vattel is not now or has he ever been God.
But some people worship Vattel with the same enthusiasm that they worship Trump.
This proves you’re wrong regarding Vattel.
https://www.courtlistener.com/?q=Vattel&type=o&stat_Precedential=on&order_by=score+desc