The person harmed by an experiment is not made hypothetical by being included in an ethical debate.

Discussing a harm in the abstract does not make the harmed person abstract. They remain a specific human being with a body and a life, whatever the argument concludes about acceptable risk or the greater good, and the calm register of the debate can obscure that in a way the debate then never corrects. Reasoning about people has a way of thinning them.

Whenever you find yourself weighing costs that will fall on someone else, try naming a real person who would bear them. Ask whether you could say your reasoning to their face, in those words. If the argument only works while everyone stays hypothetical, that is a serious sign about the argument.