I think Rudy did actually get it but Barr is AG and Rudy is not. Chain of custody is important but transfer is not forbidden. They can get it but it depends on how it is obtained.
Maybe Rudy just made confirmations and the AG is acting on them. There is absolutely NO ONE they can trust, is there?
I think Rudy probably located the server, but didn’t take physical control of it. He passed the information on to Barr and the DOJ will physically take the computer. This eliminates a messy chain of custody issue.
I’m betting the Solicitor-General of the Ukraine grabbed the server early in the corruption investigation and it has been sitting under lock and key somewhere.
Rudy can verify the existence/location of the server without tipping the information to the Deep State. This is going to blow-up rather quickly which is why the Democrats are trying to control the news cycle.