They’re not wrong. The US worked very closely with fascists post WW2. High ranking Nazi officials were recruited to run NATO, NASA, and work in many other agencies. It’s not limited to Nazi’s either but other fascists as well. In Japan the US helped a war criminal become prime minister. This guy was literally in Tojo’s cabinet and was a signatory to the declaration of war against the US. Partnering with fascists is something the US still does to this day.
This history isn’t hidden either and the US doesn’t really deny it. However, it’s not exactly something Americans are taught in school.