Not really saying that, of course any OS is hackable, Linux also is not normally a RTOS with the exception of RT Linux, and possibly some other specific distro'

Not really saying that, of course any OS is hackable, Linux also is not normally a RTOS with the exception of RT Linux, and possibly some other specific distro's. What I was trying to say is that something that has a more direct connection to the device is less likely to be prone on this specific kind of attack, which is AFAICU a sort of MITM (displaying a loop of the recorded display), and of course with a very "vertical" and "dedicated" operating system there should be less chances of the "casual" insertion of a USB stick in it (and possibly even no USB port at all on the actual hardware used).