If this ever becomes law
You can no longer bring any electronic device with you on a flight to/from 'Murica. The fact that it is outside of your control for quite an extended period of time means anything could have happened to it. It is, essentially, no longer your device.
Firmware updates, hardware keyloggers, anything is possible. They already require your bags to be 'locked' in a way that they can be opened by anyone with a master key (the TSA and anyone with a 3D-printer). They can thus do anything to your device without detection.