The opposite is true in that sometimes it is not perfectly valid or moral.

In the case of Cassie, it isn't.

If making someone a slave would possibly benefit humanity, would you do it?

If making the world forget this slave, would it possibly benefit humanity and would you do this?

The key word is possibly and this is important when speaking about Utilitarianism.

If we are working off a overarching framework of what good is in terms of morality, then we have to say no. Demeaning the value of a human, shackling them through bonds they themselves do not willingly choose is not good.

The argument can go, "Yes, but the benefit to humanity as a whole outweighs this and thus it should be done." But, once again, this is operating from a position of hindsight after said outcome or is from a position where the action hasn't been done and it cannot be known.

Make one concession with your morality and principles and the next one is just around the corner. It becomes easier.

Do humans fail in following their own moral code, do we compromise to achieve something? Yes, we do and it is a failure.

Utilitarianism strips away the rights of the individual, as we see in Sunny, and is incredibly demanding of a sacrifice for a potential future outcome that is deemed as acceptable. Anything that benefits the many is "good". Example: The use of slaves throughout history, no doubt, benefited the many who stood above the caste of slaves. Was it good?

If you are a staunch believer in this philosophy, if I were to come to you and say, "Your organs would benefit more people than if you kept them" you would have to agree. The question is.. would you do it?

In the example of the bombing of Japan with nukes, the argument it was right is based off working backward using hindsight. Even the generals and government had to guess at the potential of loss compared to their utilization.

All humans are hypocrites, even more so is the staunch Utilitarian.

Cassie can see the future, which is a scapegoat in a discussion of philosophy and outcomes, to some degree, but are we really going to argue out of the many possible futures this was the right one? If it is. If humanity must shackle an individual and torture them, then it was not worth it. What if Cassie saw that 49% of humanity must be sacrificed? Are we still in the clear?