Yes, we've all considered 'extraordinary rendition' and 'unfortunate accident'.
Problem is, he spent 600 days in the UK where he traveled a fixed route on foot, in a rural area, at a set time every single day (when he was reporting for bail). If there was going to be an extraordinary rendition, or an accident, it would have happened there and then.
Likewise with a US extradition request, which would have competed with the Swedish one (leading the Foreign office and the judiciary to come to a decision) at least right up until the final Supreme Court ruling, two days before he ran to the embassy which made the Swedish extradition final and permanent.
Also, more fun facts, every one else investigated by the [now disbanded] Grand Jury, has had no such fears, even though they did the actual work on the cables and videos, and didn't just write a press release. Some even visited the US in 2013 and had no problems, no arrests, etc.
If you have (or had) little kids, you'll understand the bedtime problem. Every time it's bedtime, there's something else that just came up that means they can't go to sleep; they're hungry, they want a glass of water, there's a monster under the bed, read them a story etc. The claims about the US are nothing but 'monster under the bed is going to eat me' claims.