Let's say that D is a random variable representing whether a certain person in one of these black sites is dead due to mistreatment. It's not so simple that D=0 if the guy lives, D=1 otherwise, D is a continuous variable, a damage level.
You can't sample from D ~ P(D) because people aren't releasing such information; and we know this, because when El-Masri sued the US he was prevented from doing so by means of the State Secrets doctrine and it was argued that whether he had been tortured and by whom was a state secret. Consequently what we actually have samples of is P(D|released) and I think P(D|released)=P(D|innocent,recognized as innocent,slightly lucky). So if we have D ~ P(D|released) where it turns out that we have observed a realization of that with D = 0.17, do you think there are only a few outcomes where D=0, when taking into account that E[D|innocent,recognized as innocent] should be much larger than E[D], and when taking into account that P(released) is really small, something like 10^-4 or 10^-3?
This is not a real thing, it's just something you made up. You can see this obviously if you transfer this to another domain. For example, if I get a paper cut at work do you think that means I'm partially dead? Do you think that singular example of a paper cut means "we can be fairly sure" that "a bunch" of my coworkers have died from paper cuts?
It's ad hoc, but so is all maths, and all reasoning.
A man with a paper cut is at D=0.9999 or more. You probably have more noise from variations in sleep or eating or colds. But people don't end up at D=0.17 just randomly. El-Masri was in danger of dying. The fellow was actually tortured.
There's also no censorship in the example of the paper cut. It also isn't possible to infer much from a something like that E[D|some positive condition]=0.9999, so even if there were censorship your example with a small scratch doesn't allow the sort of argument I gave in my previous comment. My previous comment specifically relies that you have a censored sample D~P(D|something that you'd expect would make D large) and then finding that this D is small.
Still, I think there's a point to this statistical reasoning: Assange could have made it at the time, and been correct, and thus we have a strong argument for his duty to act under Icelandic law.
There's a guy from Lebanon who ended up moving to Germany called Khaled El-Masri who got seized in Macedonia by the US and who got sent around a bunch of US black sites.
Eventually people figured out he wasn't Khalid Al-Masri and started treating him better, but he still almost died. Consequently, the people who weren't treated better almost certainly did.
This can't really be disputed. The US certainly killed people at these black sites. The obvious danger El-Masri was in makes that clear.
There is a screw-up in my previous comment since I say Poland rather than Macedonia or Afghanistan, but there's reason to think that the Polish black site is iffier than the others because of how the investigation of the location was performed.