> The part I don't understand about this view is why would Sweden be more likely to extradite him to the US than the UK would?
Sweden has cooperated with handing political asylum seekers over to the CIA, knowing they would be sent back to Egypt to be tortured, in blatant violation of Swedish law and international obligations. Wikileaks published documents showing that years after CIA rendition flights had supposedly stopped, the US ambassador had been officially summoned to receive a complaint after Swedish military intelligence had uncovered that they were still happening, with the knowledge of airport staff.
Meanwhile, in the UK, there are extradition cases that have gone on for a decade with no resolution, as UK courts take this very seriously, and a substantial portion of extradition requests from the US are refused.
To add on to that, consider the behaviour of the Swedish police and prosecutors. Maybe they are just inept. Maybe there are other motives for how they've acted. But if you're someone like Assange, who has seen several US politicians calling for him to be executed, coupled with past illegal handovers from Sweden to the CIA, it wouldn't be that strange to get a bit paranoid about things such as why the case was reopened after it had been closed, and why the prosecutors categorically refuse to interview him abroad, when they've done that for substantially more serious crimes.
Personally I think that the most likely explanation is not US involvement, but "just" political point-scoring by the prosecutor and appointed lawyer for the alleged victims, both of whom have a history of trying to get support for making Swedish laws regarding rape substantially stricter.
