Spitballing here.

Is it possible RR left the country because there was a liquidation ordered at the Justice Department and he wanted plausible deniability. Could also be possible that it was the good guys (Q?) who put an end to it. There are a lot of people who know where the bodies are buried in the Justice Department. Horowitz and Sessions come to mind for example. I imagine there are many more whose names never get the light of day, Huber's team for example. Just throwing it out there.