In the books, scientists clinically discuss killing. That apparent heartlessness is the flip side of the objectivity required by the scientific method.
But let’s start with a scientific joke about Giraffes:
Regarding scientists, this is from a brief biography of the brilliant Irish physicist and molecular biologist John Bernal (my emphasis):
(In World War 2, he teamed up with)…Solly Zuckerman, best known at that time for his studies of apes. During the course of the war they would together undertake a whole series of important assignments, but at this moment they were looking into the precise effects of bombing both on people and on buildings, into which it seemed very little research had previously been carried out. Their immediate concern was a casualty survey for which they would travel up and down the country to wherever some incident appeared to demand investigation…
That led to the British strategic bombing campaign explicitly targeting the homes of workers rather than the factories in which they worked. It was very effective.
So Vincent, David, and the designers of the Rat missile are quite normal, as scientists go.