Re: Makes no sense
"It would be an insult to Sweden to ask it for such assurances, because if Assange is extradited under a European Arrest Warrant then the receiving country cannot extradite him without approval by the sending country. "
Firstly, I don't think the issue of Sweden taking offence is really important. They might say it's not required, but if they have no intention of doing it, and it gets the extradition done, what's the problem? I'd happily give an undertaking not to do something I had no intention (or believed could not do) if it gets a stalled situation moving. And as I pointed out, many other countries, including the US, give assurances - that they won't consider the death penalty, or evidence obtained by torture, when those may usually be permitted in the country. So they are essentially prejudicing the case, in order to obtain the suspect.
Regarding the European arrest warrant, indeed the UK would have to give permission. But who would be required to give such approval? The UK government? Or the courts? That's important, because there have been high profile cases where people have been prevented from being extradited from the UK by the UK courts (Abu Hamza springs to mind, but also some hacker cases) against the wishes of the UK government. So in the case of Assange, that probably needs to be settled.
If it could be confirmed that the UK courts would get the final say on whether to give permission to Sweden to extradite Assange to the US, or have jurisdiction to hold the UK government to account and prevent them from giving such a decision, then Assange would clearly be no worse off in Sweden than in the UK. But if it is purely down to the UK government, and the UK courts have less jurisdiction over that than they would if the extradition was from the UK to the US, then it's reasonable to say that Assange would be at more risk of extradition from Sweden to the US than he would from UK to the US, taking account of recent decisions by the UK courts over extraditions to the US.
Sweden giving an undertaking would of course nullify any such arguments.