Re: Is this the best that the USA can come up with ?
The US-UK extradition treaty does contain provision for competing requests from several countries (Article 15). It simply says it's up to the UK, in this case, which takes precedence after taking in to account all the factors.
Complicating factors with the EAW are Brexit obviously, and the fact he's presumably not classed as a British resident which might preclude him being returned to UK custody after visiting Sweden.
Biting the hand that feeds IT
