What matters to practice is not what the law "is" but what the "perception" of the law is. While the actual legal risks surrounding unilateral refusals are remote, the perception is that the risk is material. I suspect this is due to cognitive features like salience. Baby K had such a high profile, that while distinct (since most futility cases involve ICU and other inpatients not subject to EMTALA), it is thought to “control” these situations.
People's behavior is guided (1) by what they think the law is, (2) by what they think the chances of enforcement are, and (3) by what the sanctions are. Less important are (a) what the law actually is, (b) what the chances of enforcement actually are, and (3) what the sanctions actually are.
At some level, I am hoping to change the perception of risk both through education and through establishing safe harbors like regional ethics committees.