Evidently, they have to formally question Assange before filing charges. They'd rather have him in custody in Sweden before they do that. Isn't it pretty well established by Assange's own actions that Assange would be a massive flight risk? The Swedish aren't the ones acting irrationally.
First of all, you can be charged in absentia in Sweden. If they interviewed him, and he still refused to return, then that would be a textbook case of a justification for having him charged in absentia.
Secondly, he claims that he will be extradited to the US if he is brought to Sweden. How exactly would he suddenly become more likely to try to flee if they decide to charge him? He is already claiming that going to Sweden means a risk of facing the death penalty in the US.
In that context it seems ludicrous to think that interviewing him and then charging him would somehow increase his resolve try to avoid extradition, or that this has been the case for a very long time.
It is not like he would have considered voluntarily setting foot on Swedish soil from any point over the past year or more. A charge would not have made that more or less likely.
Meanwhile, a formal charge would remove at least some reason to question the motivations of the Swedish prosecutor, and it would make it much harder for Ecuador to justify asylum given that they have publicly used this as part of their process for determining whether or not to give asylum.
As for that. At the moment he is holed up in a small embassy, while the Metropolitan police is outside, waiting for a chance to grab him.
Yet the Swedish police still refuse to interview him, while making up bogus excuses for why they don't. They could have stated the reason you suggest: That if they make the decision to charge him, they want to be able to take him into custody immediately under the circumstances. That reason is still a poor excuse, but they've not even tried to use even that.
If he is a flight risk in his current location, he is a flight risk whether or not they interview or charge him - his only realistic means of escape is if he gets asylum from Ecuador and Ecuador finds a way of getting him on a plane, whether smuggling him in an oversized diplomatic pouch or convincing the UK to give him free passage. Either way, this doesn't become any harder or easier depending on whether or not Swedish authorities interview him.
The Swedish might not be the only ones acting irrationally. But if they're not acting irrationally, it would imply they have a hidden agenda. If their agenda is what they claim it is, then yes, they are acting irrationally. Either alternative is pretty bad.
So in the absence of information, we assume it's a CIA conspiracy? What?
OK, maybe it's a little irrational that the Swedish prosecutor doesn't want to bend over backwards and do it Assange's way just to humor his paranoid delusions. But it's not suspicious.
