This is the text if the actual Swedish extradition law from the government web site. It clearly states on Page 3, section 12, point 3 that someone can not be extradited if they are to face the death penalty. The Swedes would have to get assurances from the US that this wasn't the case to extradite him.
Sweden has been breaking international law for some time now, at the USA's behest. As the UN panel noted there is no reason to think Sweden might uphold their own diplomatic assurances as they have been caught violating them repeatedly.
http://wlcentral.org/node/2671
It seems to be supported by evidence, and has been posted by sources that are trustworthy. It would be cowardly to post something like this under a pseudonym.