More generally, one does not build an empire (broadly construed) by being moral and ethical. We see this in at least two different ancient mythologies. https://twitter.com/pryelluw/status/1334617729798721536

The first is the founding of Rome. In some versions, Romulus killed Remus in a dispute about where to build the city (other versions have a supporter of Romulus so the deed). Thereafter, Romulus founded Rome.

The other myth involve, perhaps the more familiar Cain and Abel. Recall the dispute was over whether god preferred a farmer’s sacrifice ( Cain) or a Shepard’s sacrifice(Abel). Cain then killed Abel. After that, Cain found the city of Enoch.

Both stories feature fratricide, followed by founding a City. Moreover, in the story of Rome, the brothers attempted to settle the dispute through an agreement to seek the gods' approval through a contest of augury. This is similar, if you view Cain and Abel’s sacrifice contest.

More over Cain and Ables contests could be thought of as a contest over what kind of land should be cultivated, farm land or grazing land. There are likely more interesting parallels we could draw. It is likely that there are other instances of fratricide followed by building.

That is not to say all building of such structures (especially at smaller scales) is always immoral or unethical. But one should be wary however.