Oppenheimer didn’t order the bomb dropped. But the truth is that very few understood the horrific power of the weapons. For a vast majority who knew of the bomb, it was just a bigger more powerful weapon. It wasn’t anything unique or otherwise game changing. It was just a really powerful bomb.
And it followed that explosives had been getting more powerful. First was black powder. Then modern gunpowder with nitrates added to the basic formula of Black Powder. Then nitroglycerin. Then dynamite. Then TNT. Composition B. Plastic Explosives. Then Atomic Explosives.
It seemed like a rational and normal progression to the minds of the era. And like children, they had to be burned by the hot frying pan on the stove to learn what it was like.
Oppenheimer realized that while the scientists understood how awful the weapon would be, the politicians and military people never would. He endorsed the dropping of the bomb because there was no way to stop it, and only by agreeing could he stay in the discussion about the future of the Bomb.
Look what happened when he opposed the development of the Hydrogen Bomb. He was called a Communist and a security risk.