Doesn't help to threaten doctors, but it does help to have family there as much as possible.
You've got a point that threats can be counterproductive, but simply having family members there is not necessarily that helpful. I stood right there and watched as the nurse gave my mother the shot that shut down her breathing and sent her into her final downward spin. I didn't know what it was or what the side effects might be. It is only helpful to have someone monitoring if they have a clue what is going on medically -- which I did not.