There's an interesting distinction between removing life support and not supplying it in the first case, and a number of grey areas involving the desires of the patient; but taking that at face value:

Is the party not-in-power really the responsible actor?

But to summarize what I understand of your position: There's no individual mandate to action, as that's covered in state action. Also, raising taxes has either trivial social costs, or costs small enough to be outweighed by the (assumed) benefits of universal health care.

Is that pretty close to what you mean? Obviously I disagree on a lot of it, but that's different from not understanding your position in the first place.