I can't even elderly-proof it. Apparently if you spam the mute key it suddenly will spawn a random accessibility menu you can jam settings on in the OS itself (going past the cablebox and my CEC controls). Even if I do everything I can to restrict the remote down (universal remotes, etc), I can't disable that shortcut.
... so I keep getting calls that the "TV keeps talking by itself" every time they hit a button and it fastspeaks everything on screen (VOLUMEDOWN VOLUMEDOWN VOLUMEUP VOLUMEUP MENU MENU etc) because they managed to turn on settings they shouldn't have been able to get to. :)
You elderly proof it by hiding the TV remote and having everything controlled by the device driving the display.