If you don’t believe in God, and you think that life is simply a matter of chance, then what is the difference between a human and a roach? Nothing of significance.
“There is no moral justification why the opinions of judges, lawyers and doctors should override those of the patient [who has expressed a wish to die],” she said,
...is completely logical and irrefutable, IF you think that Human Beings are the ultimate arbiters of their own morality. She believes this kind of thing because it is a natural outcome of the presuppositions she has about the nature of life. Unless she can be persuaded to rethink that, there's no point in arguing over a relatively minor application point like assisted suicide.