[PL 431] "Playing God" and Life Support

One argument against the moral permissibility of euthanasia goes roughly like this:

1. It is morally impermissible to take direct action designed to kill a terminal patient.
2. Active euthanasia is taking direct action designed to kill a terminal patient.
3. Therefore, active euthanasia is morally impermissible.

On the other hand, passive euthanasia is taken to be morally permissible, at least sometimes.

1. It is morally permissible to withhold treatment from a terminal patient and let nature take its course.
2. Passive euthanasia is withholding treatment from a terminal patient and letting nature take its course.
3. Therefore, passive euthanasia is morally permissible.

The active/passive euthanasia distinction is often motivated by "playing God" considerations. That is to say, it is argued that directly killing a terminal patient is "playing God," i.e., intervening in the natural course of events, whereas withholding treatment is simply letting nature take it course.

If this is so, then why not let nature take its course when terminal patients need to be put on life-support? In other words, are those who appeal to the active/passive euthanasia distinction committed to something like the argument below?

1. It is morally impermissible to take direct action designed to prolong the life of a terminal patient.
2. Putting a terminal patient on life-support is taking direct action designed to prolong the life of a terminal patient.
3. Therefore, putting a terminal patient on life-support is morally impermissible.

Is putting a terminal patient on life-support "playing God" (i.e., intervening in the natural course of events) just as active euthanasia is claimed to be?