GD's findings on trailer anti-sway control and other systems has some merit to it. And makes one stop and think about it.
The truck is so integrated now with all these subsystems, it may not expect the driver to press the manual control button on the brake controller. And if the driver did do that, the manual action will change the yaw reactions of the system which it will do. But the input sensors to all the subsystems will also react and they try to reduce or induce something. Technically, they should have some kind of software to sense manual button being depressed and what to do with that.
This may be like the change from older non anti lock brakes to antilock brakes. Years ago, you were taught when driving in snow/slippery conditions to pump the brakes to not skid and lock them up. But when anti lock brakes came out, that is not what you do, you hold for foot steady and let the anti lock feature do its thing. And the first time you drive one, that ratcheting feeling in the front end is all "new" and foreign to you. No one really tells you all this when you buy a new car on the dawn of a technology change.
Thinking through all this, one needs to understand what is in a new truck with all these subsystems. They also need to use better language in the owners manual when the proven older ways that even Ford preached, have changed on the use of the manual brake button. A statement saying to the effect, the auto features of the new intergraded systems can be interfered with if the the manual brake control button is applied while under way. See pages XYZ on trailer sway control etc. Or something to that effect.