Key point. Other legal privileges expire at death, this one should also.
The privilege expired. The math hasn’t.
This isn’t about "privileges" it’s about the immutable laws of encryption math. AES encryption has but one key. . . and it’s binary, either yes, or no, on or off. It’s either encrypted and safe because no one else has the key, or unsafe because anyone might have your key. You provide a backdoor, then it’s not safe.
You provide me an absolute, guaranteed secure repository of passcodes, and I might be willing to register my passcodes in it. But as the Roman Juvenal famously, wisely, and perspicaciously asked, "Quis custodiet ipsos custodes?" — "Who watches the watchmen?" And, like gun controls, only honest law-abiding citizens would register their encryption passcodes; crooks would ignore any such requirement.