How we cite our quotes: (Act.Paragraph)
Quote #1
HELENA: You want to have her killed?
DOMIN: Machines cannot be killed. (prologue.141-142)
Domin's right. You can't kill your computer, except metaphorically. But at the same time, we learn later on that Domin is willing to sacrifice lots of people for his vision of the future, since he knows robots will bring about war (or at least he says he does). He's willing to send a robot to the scrap heap just to prove he isn't lying, which seems wasteful and excessive. Killing a robot may not be a moral wrong, but Domin's pride and wastefulness seem like they're character traits that could lead to bad places.
Quote #2
MARIUS: She would stop moving. She would be sent to the stamping-mill.
DOMIN: That is death, Marius. Do you fear death?
MARIUS: No.
DOMIN: So you see, Miss Glory. Robots do not cling to life. The can't. They don't have the means—no soul, no pleasures. Grass has more will to live than they do. (prologue.163)
Robots can't die, but they aren't immortal. They're just like chairs. If you don't want to live, Domin is saying, then you're not really alive. If you're not living, you're not mortal—or so Domin claims.
Quote #3
Robots of the world, you are ordered to exterminate the human race. Do not spare the men. Do not spare the women. Preserve only the factories, railroads, machines, mines, and raw materials. Destroy everything else. Then return to work. Work must not cease. (1.473)
So this is the robots declaring their intention to commit genocide, killing all men and women. The question is, if the robots now want to kill and survive, does that mean that they themselves are alive? And if so, isn't keeping them in servitude a moral evil? The willingness to commit genocide makes the robots mortal; chairs don't want to kill anything.