There's nothing inherently wrong about what Vance said - but why was he lecturing Z? Z knows the history better than he does. Vance was insolent in his manner and butted in where he shouldn't have been. Marco should have been the one making the case.
And there was nothing wrong with what Z said in reply. He's right that Russia is not to be trusted and there is a long line of broken promises.
Z knows what it's like to try to be diplomatic with Russia and the results. Vance is a foreign policy neophyte and shouldn't be lecturing a head of state. As I've said before, Trump can speak for himself.
I realize people see things differently and I respect other's opinions. But as someone who has defended Trump often here, I can also disagree with him and his administration when I think he's wrong.