Secondly, even if you take a US centric view of things, just because someone at the Pentagon claims something is the US best interests doesn't mean it is. People say, "oh we need these dangerous AI based weapons or other countries will win an arms race". Arms races benefit military contractors but few other people. The 20th century taught us lessons about arms races and we should learn from them. The USA does not build nuclear weapons anymore, instead it invests heavily in diplomacy to prevent other countries from building nuclear weapons. For some reason, few people seem to consider that we could take the same approach to AI weaponry.
People simply underestimate the dangers of AI weaponry. Suppose you are an evil dictator who wants to oppress and enslave a group of people, and you can choose between a nuclear bomb, or a drone that has enough intelligence to hunt down journalists, political opponents, and any other dissidents that dare defy you. Which weapon would this hypothetical tyrant pick?
Yes, wealthy, powerful people at the top ranks of politics and business in this country, who stand to gain more wealth and power via the development of these weapons, support Google developing them. However, your position that since they're the authority figures, anybody who questions them is not an "adult", strikes me as extremely asinine and highly dangerous.