How do you perfectly secure data on a system? The hard drive should be encrypted, of course. Logging onto the system should use a one time password, as well as an asymmetric identifier. You put the computer in a locked room. Make sure the computer isn’t connected to the network, of course, and, for good measure, power it down. The door should have multiple locks, so that you can enforce two-person access controls, and each needs to prove their identity with a physical token, biometrics, and a PIN.
And, of course, the last thing you should do is take a sledgehammer to the computer before leaving the room.
You wouldn’t do that last step, would you? And, of course, depending on the value of the data, you probably aren’t doing most of the other steps, either. And that’s what security is really all about – finding the risk management balance where the protections are commensurate with the threats and value of the data.
I’ve found that when someone doesn’t want to implement a given security profile, they sometimes resort to the sledgehammer argument; that is, to find an extreme level of security that isn’t being recommended, and assert that the absence of that level of protection therefore justifies not adding a lower level of protection.