It would be great if he was granted immunity to testify about the DNC hack. Promise him a trip to the USA and a 30 day head start after he finishes testifying to get out of the country before they go after him for any other crimes.
What makes you think he would LIVE long enough to testify. Remember Seth Rich? (and dozens of others...)
He would have to have a 24-hour security team. There are many who want him dead - and the Clintons are near the top of that list (along with a bunch from both political parties who are totally given in to the Swamp).