If you have no secrets in the island, but you need to keep them from the rest of the world, then you need to imprison everyone who tries to leave, possibly for life. Consider the following situations:
someone becomes religious, and decides that the project opposes the will of God
someone finds out that their parents (not in the project) are sick, and wants to see them again
children born on the island who want to leave and explore the world
If you put all these categories in prison, that would be seen as quite evil, at least from outside.
Then again, horrible things happen e.g. in Saudi Arabia, and we mostly seem to be okay with that.
But I guess the problem is that if you are unimportant, then anyone can start a crusade against you, probably quite successfully if you are seen as obviously evil. And if you are important, then the governments will obviously want to send spies to the island.
If you have no secrets in the island, but you need to keep them from the rest of the world, then you need to imprison everyone who tries to leave, possibly for life. Consider the following situations:
someone becomes religious, and decides that the project opposes the will of God
someone finds out that their parents (not in the project) are sick, and wants to see them again
children born on the island who want to leave and explore the world
If you put all these categories in prison, that would be seen as quite evil, at least from outside.
Then again, horrible things happen e.g. in Saudi Arabia, and we mostly seem to be okay with that.
But I guess the problem is that if you are unimportant, then anyone can start a crusade against you, probably quite successfully if you are seen as obviously evil. And if you are important, then the governments will obviously want to send spies to the island.