I'm of the opinion that it wouldn't have mattered what claim was made. Cruzan's proposition is that a state legislature CAN require clear and convincing evidence of an incapacitated patient's wishes before denying the patient ordinary care that will result in death. Flordia law requires clear and convincing evidence for the same thing.
The Cruzan case was a sort of "opposite" to Schiavo. In Cruzan, the petitioner (Cruzan's parents) wanted to stop feeding their daughter (using, of course, the argument that this is what the daughter wanted), and argued that the evidentiary burden of "clea and convincing" was TOO HIGH, and thereby denied the daughter her right to "self-determine" her fate.
In the Schiavp case, Congress meant to cause a fresh review of the facts to determine whether or not the evidence (mostly of the patient's wishes) was sufficient to support the court order. That question, now, as a matter of judicial made law in the 11th Circuit, remains reserved to the state courts.