Asserting I don't know things is an argument you lost as soon as you made it. You don't know what I do or don't know.
Presume I do know about proprietary codes. Could my statements still be true? Yes. Indeed. As a programmer who has works with these codes, I know it is complete hogwash to just wave your hands like that. Could a malicious person screw up your car through the OBD port? Yes. Can they screw with the safety systems? No. I'm sure there are ways they could cause you lots of problems, but your brakes and airbags will still be working.
You don't seem to realize that the brake and airbag computers are physically separate devices. It doesn't help your position to just presume that the proprietary codes can alter those systems. If you were more familiar with the technology, you'd understand that all the active diagnostics are in the Engine Control Module and Powertrain Control Module, which are probably the same physical device, and that device can't actuate the brake or airbag systems; all that plugs into it is the sensors to tell it when the ABS or traction control engages, and a flag that says the airbag state.
And no, traction control does NOT involve powering the wheels. If you're in gear, the engine has to change speed for a different amount of power to get delivered to the wheels. There is nothing in the wheel that has any sort of gearing that would allow for the traction computer to change the wheel power delivery separately from the engine, and the engine responds much more slowly than the traction system. And the traction computer is still running with the ECM unplugged. I could go to the top of a hill, unplug the ECM, and as long as the battery is connected I could roll down the hill and slam on the brakes, and the ABS would work perfectly. The same computer does the parking anti-roll.
The idea that the ECM could actually turn off the brake power is funny. For bonus points, find a repair manual for your vehicle, discover where in the engine the power brake boost is sourced, and then ask yourself if it makes sense that it could be disabled while the vehicle is in gear and moving. I'll give you a hint: http://auto.howstuffworks.com/...
It uses engine vacuum. Power brakes have mechanical assist. If the engine is in gear and the vehicle is moving, there will be power brakes, even with the battery disconnected. If you have an electronic brake-assist computer, you can lose that if the battery is disconnected, but the ECM can't disconnect the battery. But even if it could take that extreme step, you'd still have power brakes anytime you're in gear and moving.
I did not say anything about firewalls, so I'll assume the whole passage accusing me of believing in magic ones was just a fantasy interlude, except to reiterate that the brakes and airbags are NOT controlled by the ECM computer that is the one that shuts down a couple minutes after you turn off the car.
The one thing we agree on.
You claim a bunch of specific facts that if true, would support your arguments. However, they're false. All the ECM gets from the brakes and airbags are sensor readings. There are no actuators connected between the safety systems and the engine computer.
I do apologize for the typo where I wrote ODB instead of OBD.