Neither was Terry Schiavo, so once again, you're missing the point.
Your abortionists analogy would have some merit if an unborn baby could chose his or her mother AND could exchange vows with the mother of his or her choosing AND could have the option of drawing a living will. Mrs. Schiavo chose her husband and exchanged vows with him. Because there was no formal living will making her wishes clear, it only made sense that the person to speak for her was the one she chose herself.