Nah! That won't work either! I can hide malware in the Network Card BIOS, GPU card BIOS, motherboard BIOS, the Hard Drive Bios controllers and EVEN in baseband OS bioses on wireless comms that runn UNDERNEATH the operating system! I can output alpha channel overlays that humans CANNOT SEE as frame-based video-data flashes on a display system which can be read by external recording systems. OR I can embed NOISE that represent data but the human ear filters out into headphones or audio streams or embed as analog as cross-talk which can be read by external systems.
I can also electrically flicker various motherboard chips to emit RFI/EMI "noise" as an encrypted data stream which the computer case won't trap BUT can be read outside a building! I have a TON of techniques to use to bypass ANY type of building and case shielding to get any BIOS hack-related captured data to an external reader!