There are several ways that the computer could kill you. Your fix only reduces the number by one.
You may wish to also plumb in some bypass valves on the brake lines in case the ABS computer decides to lock out all of the brakes. If it works in concert with the e-brake module, your emergency brakes could be disabled too.
Of course, the PCM could decide to slam the transmission into reverse while you are doing 80 in the middle of traffic. I'm sure there are other ways too.
There is a lot done in hardware and software to make sure the car won't accelerate unless you want it to. There have been no cases of ETC running away on someone. (There were plenty of cases of mechanical throttles sticking open.) Also, now most cars have brake override. If you floor the gas pedal and then press the brake at the same time, engine power is cut.