These questions can evidently not be asked within the embassy. (Ignoring the various, and I concede very loaded, discussions around the validity of the allegations.)
> Assange is a powerful and connected person, with strong support from a considerable percentage of the population.
Substitute 'American intelligence agencies' for 'Assange' in that sentence, and perhaps stick a 'tacit' in front of the word support, while you're at it.
To be clear, my point here is that Assange is nowhere near as powerful as any or all of the Swedish, UK, or US governments (or any of their agencies). However, world+dog understands that it's a bit more complicated than 'come and talk to us in our country about these dubious claims, oh and we can't guarantee that we haven't already arranged for you to be flown into Central America to not face charges for the rest of your life'.
> I am glad that that does not affect the legal process, and I would never want to live in a society where it did.
I am genuinely concerned about your understanding of the society/ies that you believe you're living in now.