It might be plausible this chip is not for spying, but rather a doomsday switch. It works like a switch which disables the whole system working correctly if ena

It might be plausible this chip is not for spying, but rather a doomsday switch. It works like a switch which disables the whole system working correctly if enabled by a simple signal. There are many critical paths on the board which can be disabled with that very simple approach. You don't even need a sophisticated IC for that.