Victor Stone: Does anybody know?
Silas Stone: What?
Victor Stone: At the lab. Does anybody know I'm alive?
Silas Stone: Uh... I didn't think you were ready for them to...
Victor Stone: To what? For them to see the monster?
Silas Stone: You are not a monster.
Victor Stone: It's weird that you thought I meant me.
Bruce Wayne: I wouldn't count of the tribes of men. We tend to act like the doomsday clock has a snooze button.
Answer: "Surely they'd figure it out" is hardly a suitable solution. If they knew how to destroy them, they would have. They did the next best thing by hiding them in different places.