> Sweden isn't legally allowed to extradite him after he's been extradited from the UK.
Can you support that claim?
My understanding was exactly the opposite. Sweden can't execute someone who would face the death penalty where they are being extradited. That's part of why Assange hasn't been charged under the Espionage Act - it would bar extradition. I'm not conspiracy theorizing there, it's been explicitly stated that extradition is a reason to delay charging him until he can be brought here to face a grand jury.
> "Sweden isn't a better country to extradite him to the US from than the UK."
This claim doesn't seem relevant. As soon as he was facing legal involvement in the UK (or as soon as he got asylum, I'm not sure how the timing shook out there), he ran for the embassy. Your implication seems to be that he's hiding from Swedish prosecution rather US law, but I've seen no indication that he would leave the embassy if Sweden dropped charges. Without that, I don't see how the Sweden/UK distinction matters - he's avoiding both legal systems which could extradite him.
This is a sincere question - I'd like to know anything backing those points. I'm not saying you're wrong, but I haven't seen anything suggesting that A) Sweden couldn't extradite, or B) Assange is willing to face the UK legal system but not the Swedish one. One or both of those seems necessary for your conclusion.