It might be useful to collect and list--in very rough order of importance--the arguments for refusing medically inappropriate treatment requested by a surrogate.
1. Prevent patient suffering: Aggressive treatment can cause significant pain and suffering. This is unaccaeptable if there is no countervailing benefit to be achieved by the treatment.
2. Protect patient autonomy (re treatment): In many cases, the aggressive treatment demanded by a surrogate is treatment not wanted by the patient. And where patient preferences are unknown, continued treatment is not in the patient's best interests.
3. Protect patient autonomy (re other things): Providing unwanted treatment not only violates the patient's bodily integrity but also the patient's autonomy concerning the location and manner of her death (ICU vs. home). It also causes the utilization of estate resources to pay medical bills that the patient wanted to go to other uses (e.g. grandchildren education).
4. Prevent family distress: Often the surrogate wants the burden of decision lifted from herself. And even if not the surrogate, other family members are often relieved to see the patient’s preferences or best interests protected.
5. Preserve the integrity of the medical profession: Those in the health profession surely must have some role in defining the ends and goals of medicine.
6. Reduce nurse distress: Numerous measures show high levels of moral distress. This can both drive people from the profession and thus reduce access. It can also reduce staffing levels and make people operate less well, adversely impactiung other patients' quality of care.
7. Responsibly steward scarce hard resources (e.g. ICU beds) to maximize healthcare access: In an under-bedded region like NM, the ICU bed used by a patient with PVS and multi-organ failure is the very same bed that could be used to achieve recovery for an accident victim.
8. Responsibly steward scarce soft resources (e.g. dollars) to maximize healthcare access: the billions spent treating PVS patients could be used to cover more people who now have no coverage. As costs rise, premiums rise, and access drops.
Of course, there are also arguments against unilateral refusals. Those will vary according to the specific circumstances of a case. Whether unilateral refusal is ethically justified, on balance, will require some sort of weighing.