"He was 100% correct"
Absolutely. It was worse than he thought. Read Venona .
There is even some indication that Robert Oppenheimer was a Soviet spy , by-way-of, Klaus Fuchs.
Also, read the book, Witness by Whittaker Chambers...one of the best books ever written.
Read Blacklisted by History by Stanton Evans
especially the last chapters on how Chiang Kai Check was screwed and China relegated to MAO
Makes you want to retch