The problem is that you're missing the point. The point is WHY are these life support mechanisms being removed? If the patient is brain damaged or brain dead, then the cause of death makes no difference since the patient is already (medically) "dead".
If the patient is not brain damaged or brain dead, then were talking about "quality of life" and euthanasia. That is not the case here, nor was it with Terri Shiavo.
Although Reeve was severely disabled from a physical standpoint he was able to maintain sound mental functions. If he were permanently disabled and had severely impaired brain function, I suspect he would have been in the exact same position as the infant in this story.