I don't see a problem with applying "modern" morality to people of the past. There's nothing wrong with saying, for instance, "people in 1950 were widely homophobic", or "pedophilia was rampant in medieval society". Just because people back then wouldn't have even identified homophobia or pedophilia as anything out of the ordinary doesn't mean they are morally excused.

Someone who doesn't know any better is still acting immorally even if they are oblivious or in complete denial about it. The victims of those "old fashioned" ideas suffered just as much anguish and trauma as they do today, and the people of the time knew that and simply accepted it.

The suits in government who authorised this torture and the men on the ground who carried it out knew full well that it caused real distress and suffering, and they simply didn't care, or they decided that the economic and political advantage to their own countries justified it.