Do you at least acknowledge that, given that the people involved don't know about it (and also won't find out about the torture later), torture is the correct option?

This is pretty hard to answer. For moral / ethical questions, I don't want to get "pure math" but also rely on intuitions, and I cannot really rely on my intuitions here as they are very much social. As in, immoral is what horrifies a lot of people. I don't really know how to approach it without relying on such intuitions. Surely I can calculate the total sum of utils but how does that quantitative and descriptive approach turn into a qualitative and prescriptive worse/better? I am not at all sure worse entirely equals the result of a utility calculation. It is not unrelated to it either, of course, my basic intuition - that wrong is whatever horrifies a lot of people - does of course correlate to utility as well.

I mean, what else is morality if not some sort of a social condemnation or approval?