Florida statutes include a requirement that actions taken be in the incapacitated patient's best interests too; and that permits natural death by dehydration.
765.401 (3) Before exercising the incapacitated patient's rights to select or decline health care, the proxy must comply with the provisions of ss. 765.205 and 765.305, except that a proxy's decision to withhold or withdraw life-prolonging procedures must be supported by clear and convincing evidence that the decision would have been the one the patient would have chosen had the patient been competent or, if there is no indication of what the patient would have chosen, that the decision is in the patient's best interest.
Chapter 765, Florida Statutes 2004 <-- Link
But you were taking her "statement" as true, while questioning anything that might mitigate the WND story.
Yes, best interests is a subjective term, but virtually anything in medicine is somewhat subjective. The fact that doctors in the Schiavo case disagreed on the extent of her PVS diagnosis proves that.