Partially correct. Lisa McPherson was starved and dehydrated to death after she suffered an emotional breakdown at the age of 36.
In Scientology, when a person falls to 2 or below on the Emotional Tone Scale devised by L. Ron Hubbard, they cease to be worthy human beings. Scientology preaches the utopian notion of a fit, healthy, able-bodied and perfect society. Mentally and physically disabled persons are afforded no rights in The Church of Scientology. They're seen as a burden on society ("useless eaters", if you will), and hence, they must be destroyed.
It's the same type of totalitarian self-help/only-the-strong-survive philosohy that the nazis use to take Europe, only its been modified for modern western culture.
It's just Lucifer, wearing a different mask and using the different tools at his disposal.
You have nailed the connection with the Cult of Scientology to their push for euthanasia. Incredible that this cult has such a following. It is a total fraud devised as a tax shelter for L. Ron Hubbard who wanted to increase his profits from his science fiction book sales.