You can't demand Julian Assange meekly face the rule of law in Sweden when there is a real possibility he will end up in the Kafkaesque nightmare of the US extra-legal political incarceration system. Greenwald discusses the obvious immediate problems that Assange would likely be held in solitary, without due process, without his US Constitutional rights and possibly even forever with or without some kind of kangaroo show trial. After all, the Executive branch has asserted the right to try people, and still imprison them even if an Article III civilian court were to acquit them.
That's just what Assange might face under President Obama. Leaving aside the discussion about whether solitary confinement is necessarily a form of torture, a President Romney or Ryan or Generic 2020 Republican could just re-activate the Bybee memos and have the CIA dust off the waterboards, unshutter the cold rooms and freshly oil the "stress position" chains. Or worse. After all, by their decision not to prosecute the people behind the Bush administration's torture program, Obama has reduced the torture question to a mere partisan and policy issue. Who knows whether some future Republican President will decide to employ torture again? An Assange in US custody would have to consider not just the next year or two, but possibly the remainder of his life.
Basically, the United States is a place where the rule of law is set aside for political prisoners. Assange would certainly be one such. And yes, I know it is Sweden seeking his extradition, but their hands are far from clean on the subject of dubious American extraditions.
As Greenwald, Michael Moore and some others have recently noted to those concerned that Assange's asylum would deny justice to the two women in Sweden who have claimed he raped them: It is the refusal of Sweden to rule out extraditing him to the US, and the refusal of the US to rule out seeking his extradition that are the cause of this. Assange may be a bad man, he may be a sexual criminal, but liberals don't make torture acceptable punishment for rapists (or spies if you buy that sophistry). We don't accept holding accused rapists in solitary, for life, without a trial (or a fair trial) as legitimate punishments. Eliminate those unjust possibilities, and Assange has no more excuse to avoid facing his accusers in Sweden.
The United States chose willingly to engage in torture. It very deliberately created a set of ridiculous legal memos to provide legal cover, it went through rounds of development to find torture practices it liked and it used them on politically selected prisoners. It set up secret prisons all over the world and a secret "airline" to shuttle people around within it. Liberals (once aware of it all) warned that abandoning the rule of law would have (among many other harmful outcomes of using torture) credibility implications and now here they are.
Who can trust America's intentions in the world? On what basis could a man who has so publicly stuck his thumb in the eye of the most powerful people in America possibly rest assured that he would face anything like humane treatment and due process if he fell within their grasp? None of this is hypothetical. Private Manning was held for 11 months in solitary confinement, and placed on unofficial suicide watch (including forced nudity) as punishment for a sarcastic remark. He has now been held for more than 2 years without being yet being actually tried. The 6th Amendment guarantees timely trials, yet not for Manning evidently. Manning is actually an American citizen and this what he faces. What protects Assange from being sent to Gitmo or Bagram and denied even the modicum of due process given to Manning?
These questions would have been absurd prior to 2001. They're real issues now.
I've heard some say that Sweden has no obligation to rule out extraditing Manning, as they have a treaty with the US, and why should they make a special declaration just for Manning, a possible violation of their treaty? Well for one thing, Manning clearly is a special case. How many people have published hundreds of thousands of pages of US government classified material on the internet? But more importantly, the above concerns are plenty of legal and ethical justification for Sweden to rule out his extradition to the US. One of the links above concerns the condemnation Sweden received for extraditing prisoners to a place where they faced torture. That's a well understood principle in international law. It doesn't have to even be torture, just lack of due process is sufficient grounds to decline extradition.
Finally, no, the fact that the US has not announced some desire to extradite Assange does not make this all a "conspiracy" theory or some wild notion. The US has "sealed indictments" precisely for situations like this, where they don't wish to alarm the target by letting them know they face serious charges until the authorities are ready and able to capture the person. In some circumstances, this is surely sensible. No reason to let someone destroy evidence or flee the country if it can be avoided. There are credible reports of a US Grand Jury focused on Assange. The Obama administration has been noted for its aggressive prosecution of (unauthorized) leakers and (ab)use of espionage laws against them. All the necessary elements are there: motive, means and now they just need the opportunity.
Assange would be literally gambling his life to take the chance that the US is not planning to extradite him. If he was facing due process and established western legal practices, I would agree he is morally obligated to face that risk in surrendering to Sweden, but no one is obligated to hand themselves over to a lawless system set on putting them on show trial. The seriousness of the crimes attributed to Assange do not change this. Whether he was charged with jay walking, tax evasion, rape or murder in Sweden would not matter in this regard. He faces the risk of being tortured. Anyone sane would balk at that through whatever means they had.