I already have. Why do you think I used it together with being able to sustain life? Homeostasis conceptualizes a living things ability to maintain its own life support systems.
Look it up and throw in "requirement of life." Maybe you will learn something.
No, that does not mean someone on temporary life support is dead and again if you assclowns have a problem with it then take it up with the biological community.
The zygote may be able to maintain homeostasis as a zygote, i.e., safely in the womb of the mother and with the aid of the placenta it may be able to sustain its existence as a zygote-blastocyst, but it can't do it as a human and until the fetus (at a much later stage than zygote) can its not properly classed as "human life." That's what Wolpert and the numerous other biologists i have referenced were saying.