They can charge him and try him in absentia and wait until he enters a US extradition treaty country and put a Red notice on him through Interpol, either way it would be "enjoy hiding out in second and third world countries until someone with guns trades you to the US".

But it's just money laundering, white collar crime, minimum security prison, if he doesn't find a way to get out of the charges by flipping for a bigger fish he should just face the charges.