Not buying it. (Also EU law would prevent Sweden from extraditing him to the US without British consent anyhow. So either Britain is okay with his extradition and there's no need to get him to Sweden, or they're not and there's no point. And that's not even touching on the fact that Sweden couldn't extradite him to the US without an assurance that he could not face execution, which is politically very unlikely to happen. I don't doubt the US would love to grab Assange, but the legal extradition question is a complete red herring.)
Edit: Fix dumb typos, too tired.