Well more broadly the US had to adapt far reaching initiatives that were close to National Socialism to win the war. You had governments controlling everything through rationing, cracking down on war desent, domestic spying yada yada.
And following the war the importation of German scientists and specialists continuing working under those same initiatives bleed into and influenced those programs, that they became the same things the US fought against. The American space race was a continuination of the German rocket program, for example.
I'm wondering what some of the smart people on this forum feel about this theory
You're confusing Senator McCarthy with the House Unamerican Activities Committee. McCarthy went after government employees, mostly in the State Department and often confirmed by the Verona Papers after the Cold War ended. HUAC, originally formed for the brown scare we had before the war, shifted gears to go after reds instead and mostly went after random people in the entertainment industry.
This was an intentional misinformation pushed by lefties. Even though McCarthy had nothing to do with the HUAC propaganda often paints him as having been in control of it.