I think you missed his point. He wasn't saying that we shouldn't have mobilized U.S. manufacturing to defeat Hitler. He was saying that if we did it for military purposes then, we can do it for peaceful purposes now.

He's right, of course, but naive. Sure, we could mobilize for peace if we had the national will, but rallying people to do something proactive isn't as easy as getting them to respond when attacked. Pearl Harbor was a great motivator.