Duress sacrifices are a known and familiar concept. There are a couple of flaws with the concept:

* It's only as useful as the sacrifice data is convincing. This might be difficult in an active and rapidly shifting warzone.

* It only works in an environment where the attacker doesn't know such a thing is possible. If the attacker is willing to keep torturing until they get what they want, they will. Even if it doesn't exist.