First of all where does NATO come from here? Why would he fear NATO? It sounds to me like you just added that in because it's something that puts the UK in the same group as the US.

Where would you suggest he should go?

UK courts have a long history of letting extradition cases take years and/or denying extradition, and UK courts have a history of reacting to political pressure by standing firm rather than yielding. There are few places where I'd trust the legal system more.

Which other countries do you think have courts willing to stand up to political pressure, and where the US can't or won't just pick him off the streets without causing a major diplomatic crisis, and that would be somewhere you'd be able to get visas and where you'd want to live?

I can't think of many countries that'd fit those criterias. Most of the places I can think of where I'd believe the US would be unlikely to be able to get at someone are places I'd rather not want to live.

But the UK would be high on my list of places where I'd feel the risk would be low.