Prior to her collapse, a feeding tube was not legally "life support," so even if she asked to be removed from life support, her request cannot be legally construed so as to unequivocally conclude that she wished removal of a feeding tube.
But, if she asked not to have it [feeding tube], it ain't murder - not even by the Vatican's definition.
I am quite sure you are mistaken on the Catholic church's position as well. It holds that facilitating a hastening of death by withholding basics that support life (food, water, air, shelter) even if it is the patient's wish, is morally wrong. Legal? Maybe. But a good argument can be made that Terri's demise was against the legislative intent expressed in the totality of Florida's Section 765.
The courts and Mr. Schiavo could, and did, make suggestions of what Mrs. Schiavo *would have* wanted.
If they'd believed that Mrs. Schiavo would have wanted to live and receive treatment, it would be ridiculous to say, "that therapy wasn't available back then so it doesn't count"...