There's a fairly public trial now though, and this is what the US was trying to avoid with the Sweden route.
Sweden has provided it's own police to assist CIA operatives in black bagging it's own residents against it's own laws and process and sent them to an Egyptian prison clearly to be tortured and then blamed it all on a dead politician.
https://en.wikipedia.org/wiki/Repatriation_of_Ahmed_Agiza_an...
I have the impression that the UK government genuinely (and incorrectly) believes itself to be in a position of strength, at least for now.
To the extent that it is now sycophantic towards the USA, it already was — the “special relationship” meme in UK politics has been around for a long time.
Does this not effectively prove that? The US has made a decision, and like a good vassal the UK judiciary is delivering Assange to them.