(with the unstated assumption that the US was just in its choice to fight the Axis)
I actually don't think Smedley would have changed his message at all; I think he started from a false premise that he was 100% convinced of, and would have pointed at the enormous profits made by war industrialists in the US during WWII. He might not also notice that post-war US was the most economically productive country of all time, that it opened up huge options of African Americans, or even really recognize quite what motivated Hitler and the Nazis.
The USA started selling weapons to the allies long before it entered the war.
This is AFTER the allies attempted appeasement. If a foreign country wants to war, you can't not war. The only alternative is to roll over and accept new ownership, but usually new ownership disagrees with the people on how things should be done, so that "solution" largely isn't.
There was a period were Germany seemed unstoppable remember.
But what is undeniable is the US exited WWII in a very good position and lots of profits were made.
Your facile equivalence is rejected with prejudice.
It's your facile equivalence, that because these specific things don't apply to the US, American imperialism was morally justified.
You could just read the Wikipedia article on American war crimes, or learn about how much of the Nazi's ideology was based on American eugenics and racial segregation, or take even a glance at the last several decades of American militarism throughout the Middle East, but I guess you won't.
This is explicitly not a support of the parent's comment. The US was not great, and even had explicit segregation, but was not trying to spread it's own abysmal ideals to all of europe. Hitler was clearly trying to spread facism through all of europe, and eventually the world. His desire to do so was broadly popular in Nazi Germany, so the country's people were never going to stop him. Going to war to grind Nazi Germany into the dust was the only option. It is justified. We also didn't preempt anything. We sacrificed two sovereign countries hoping to avoid that war, which should be clearly not acceptable.