Final answer:
Bob Wilson was startled by Oppenheimer's comment because it contrasted with the often dehumanized view of the Japanese and highlighted the forthcoming civilian suffering.
Step-by-step explanation:
Bob Wilson was startled that J. Robert Oppenheimer referred to the Japanese as 'those poor little people' because, within the context of the atomic bomb's creation and use, this phrase indicates a sudden and vivid recognition of the humanity of the bomb's targets. The Manhattan Project was focused on ending the war, and scientists like Oppenheimer were heavily involved in the creation of a weapon of unprecedented destructive power. It's likely that, in the midst of scientific and strategic discussions, the vivid imagery of 'poor little people' being the recipients of the bomb's force clashed with any detached, impersonal view of the enemy, eliciting Oppenheimer's and Wilson's sense of compassion and triggering the startling realization of the personal and civilian suffering that the bomb would cause.
The discussions around the usage of the bomb revolved around multiple perspectives, including feelings of revenge for Pearl Harbor, the superiority of the United States, and deeply rooted anti-Asian sentiment. These contributed to a dehumanized view of the Japanese, making the use of such a destructive device on Japan more palatable to many Americans. However, Oppenheimer's comment reflects a conflicting sentiment, where the scientists involved in creating the bomb were also grappling with the moral implications of its actual use on civilian populations.