So the catch-22 is that he says he is happy to go to Sweden in case he is given guarantees of not being extradited, but no such guarantee is possible under Swedish law.
What swedish authorities could (and should) do in this situation is just make some really broad statements about how even though they have agreements with the USA, no one would ever be extradited from Sweden to any country in case they risked facing the death penalty and/or are whistle blowers.
So the catch-22 is that he says he is happy to go to Sweden in case he is given guarantees of not being extradited, but no such guarantee is possible under Swedish law.
What swedish authorities could (and should) do in this situation is just make some really broad statements about how even though they have agreements with the USA, no one would ever be extradited from Sweden to any country in case they risked facing the death penalty and/or are whistle blowers.