He is better off in the USA he can clam first amendment rights freedom of the press
The US position is that the first amendment doesn’t apply to non-citizens, and also that it isn’t possible to make a public interest defense to espionage charges.
also he won’t get death the worst is 20 to life
The current set of charges carry up to 175 years and the US has thus far refused to guarantee to the British court that they won’t add more charges after they extradite him.
And even if he was “only” facing 20 to life, what would that be better than? He isn’t charged with anything anywhere else.