Right, you can't tell if there is a hidden malicious component that hasn't been activated yet. You can extract assumed non-malicious data without giving a malicious component the ability to do anything, if it hasn't an build-in data exfiltration channel (microphone and wireless transmitter could spy on you without attacking your system)
I guess one could setup a jammer or some room that could completely cut off any signal possibility. However then they could put something even more malicious then just spying into the device. As much as a tin foil hat theory that is, maybe it's just best to not know what's on the drive cause it's more than likely not worth even the slightest bit of trouble. Sad the world has come to this
