He could move to Azerbaidjan or Moldova, although the latter is not that safe for him with prospects of EU integration. He could still be extradited to the EU from AZ.
I wouldn't want to be stuck there for years, to the point where even a few years in jail might be worth considering. But I'm not familiar with the conditions for prisoners in the US.
For these reasons it's probably safer for him in Azerbidjan but he will only be admitted for up to 90 days with a Russian passport. In Armenia he could stay for up to 180 days on a normal visa, but both Armenia and Georgia have extradited fugitives to the US in the past.
He doesn't have too many options.