If feeding tubes are artificial and unnatural then so are pace makers, colostomies, dialysis, oxygen and on and on. Where do you draw the line? Who gets to live or die because "it's artificial"?
I completely agree that all of those things are artificial.
Now, does a patient have the right to refuse any of these medical treatments? Or are we to forcibly install feeding tubes, pacemakers, etc. in those who do not want them?
It is, IMO, the patient's right to choose.