It's not that at all. The question is whether the cruelty can be justified in service of a greater good, or if it's just plain cruelty to satisfy aimless curiosity.
Sentient beings do not want to be brutally experimented on. This self-selecting industry of sociopaths belongs in the 19th century.
This is obviously false, because transplanting a uterus to a genetic male was done on a human, voluntarily, long before this experiment.
I can't argue whether someone should be concerned about humans or rats and how much and what experiments are worth it. How you balance one creature's suffering with another. Nobody can or has ever answered that.
I meant to counter the idea that transplanting a uterus has to be without purpose and can only be attributed to idle cruelty.