Exactly - and that maximum is the "minimum maximum" across all batches of the device. You might get a particularly resilient one that handles the 10V just fine.
The encryption idea makes way more sense, and the means to short out the cap doesn't even require the device to be powered. The only implementation challenge is that now instead of combining a simple circuit with an off-the-shelf mass storage controller, you need to either find one that can read a key from an external source or roll your own using a micro (maybe this is easy with existing libraries?). But if I was a journalist concerned about such things I'd rather pay a premium for the right solution than worry that the police might be sweating from the heat or that the chip in my drive happened to be especially resilient to overvoltage.
Back in ~2014, I had a newish 32Gb USB3 flash drive. At that time, premium mainboards had FireWire headers for front panel connectors, on board as well as USB2. Both are 2x5 headers and can easily be smashed on if the connector keying isn't really well done. The FireWire header can deliver 12v (apparently it can be "8-30v" but real PCs tended to deliver the voltage they had available). You can see where this went.
After being inserted in, the drive was dead on USB2. On USB3 it would work for a few minutes at a time. This became relevant when I discovered the drive still worked in that few-minutes-at-a-time fashion in 2021 and contained my old wallet with 30,000 Dogecoin on it.
The encryption idea makes way more sense, and the means to short out the cap doesn't even require the device to be powered. The only implementation challenge is that now instead of combining a simple circuit with an off-the-shelf mass storage controller, you need to either find one that can read a key from an external source or roll your own using a micro (maybe this is easy with existing libraries?). But if I was a journalist concerned about such things I'd rather pay a premium for the right solution than worry that the police might be sweating from the heat or that the chip in my drive happened to be especially resilient to overvoltage.