[koningrobot]

I don't think the author is talking about utilitarianism at all. They're talking about compressing their moral intuitions. They already believed it's bad to kill grandma, therefore "utilitarianism" must be beaten into shape to reach the same conclusion.

The fundamental unit of (classical) utilitarianism is good/bad sensations, not right/wrong actions. If you start by taking rightness/wrongness of actions as fundamental, you are very much not doing utilitarianism.

The grandma/surgeon examples do seem to suggest that killing grandma is good or dividing up the patient is good according to utilitarianism. That may or may not be right, depending on context -- who are the people involved, what do they bring to the table, what relationships do they have with each other and with people not mentioned in the story? You can fill out these details in ways that would lead "common sense morality" to the abhorrent conclusions also, or bite their own bullet and claim "the means justify the ends" somehow.