> Extradition was specifically blocked on the grounds of a particular regime he might be subjected to (to be fair, probably the only legal grounds on which he had any chance of succeeding). That leaves the US with a way out if they want to proceed with the extradition - guarantee a different set of circumstances.

And isn't that actually done on a fairly regular basis? IIRC, the US has pledged not to pursue the death penalty in certain cases in order to get cooperation on an extradition.