So your only problem is a verbal request vs a written one (proof of PVS is required in either situation).
Cool. You're entitled to your opinion.
But let the duly elected representatives of the State of Florida carry out the will of the people and add the verbal request to the statute. Got a problem with states rights?
States can allow a verbal request for euthanasia but not a verbal request to pull the plug? Odd.
The serious problem I have with an advance verbal request, like the one in this case, is that it is so easy for a person, like MS, to have his situation in life and his opinion of his disabled wife change to the point where he profoundly wants her gone. At that point the incentive to fabricate an alleged verbal request can become compelling and the court is basically required to determine the indeterminable.
In other, similar cases involving substantial social and individual interests the law and the courts do not take such a cavalier attitude. The two most instructive are passing property by will and transferring interests in real estate.
Each state has statutes of intestate distribution that prescribe how your property will pass on your death if you do not have a written will. Those statutes are based on the rebuttable assumption that you want your property to pass to your closest relatives. To alter this assumption you are required to execute a written, signed and witnessed will to pass the property to somebody else. Thus, if you're a sailor and own a sextant that you want your yacht club to have after you die, you must execute a proper will passing that instrument to the yacht club; otherwise it goes to your relatives by intestate succession.
The same thing's true with real estate. If you want to be legally bound to agree to sell an interest in a piece of real property you own, each state's statute of frauds requires you to execute a signed agreement to transfer that interest.
In each of the foregoing situations the requirement of a written document forces the potential testator or seller of an interest in real property to think seriously about what he or she is doing and decide, advertently and formally, what to do. Also, the law has developed this way to reduce the chance of fraud, prevent innocent people from having their vital interests affected by essentially unprovable transactions, and avoid testifying contests where it's often impossible for the trier of fact to know what really happened.
The same considerations are equally vital in the advance medical directive situation, something the Florida legislature and "right to die" advocates seem to have ignored. Innocent peoples' lives need to be protected and the law is directed to doing it by going so far as to provide the death penalty for murderers. Indeed, the average person's interest in his or her life is usually a lot greater than his or her interest in the distribution of his or her property on death.
Thus, it is entirely reasonable to establish a rebuttable presumption in favor of life in a disability situation. It would be equivalent to the presumption in favor of intestate distribution of assets on one's death and similarly alterable by a written, signed and witnessed instrument. This requirement would force the individual who wants life support to be terminated to think clearly about the situation and its implications and come up with a fully informed consent. It would also prevent the kind of testifying contest, with its attendant risk of an innocent woman being killed without her consent as a result of perjury, that developed in the Schiavo case.
The Fourteenth Amendment prohibits states from taking life without due process of law. The Federal courts have taken this as allowing them to prescribe extensive due process safeguards surrounding the execution of criminals. Hence, they clearly have the same power to review state statutes that allow the killing of innocent people and apply appropriate due process safeguards, which ought at least to include advance written directives that meet up to the standards of wills.