*Spoilers* The Torture Victims

[superluser]

And if Daniel is a scholar and archaeologist, shouldn't he have developed some skills of observation?

The concept of higher education that we have today is not exactly what it was in the 19th century. A lot of it was just a club for rich parents to dump their children (at least in the US). Some of that changed after the GI Bill, though then it became job training, not scientific inquiry...

rigid Victorian morality

Victoria having become queen two years prior. And we don't know how long he was in Algeria. Also note that public executions were conducted in England until 1868. It would not be as difficult to get someone to be an executioner if he had seen it routinely in public. From there, torture would have been less difficult to get him into.