He is also a realistic. You should read his auto-biography to see when he realized the Great Britain had become a second class country.
Without US, there is no way to defeat USSR.
But US people would not agree to attack USSR in Spring 1945. Whether Truman wanted or not, US voters will not agree. At that time, USSR was an ally. The average US citizen is quite foolish. They were not ready to fight an anti-communist war. Propaganda takes time. Churchill knew that. He spent much time in 1945-1947 selling his 'anti-communist' ideology.
This chalatan USSR historian just wanted to justify Stalin's 'greatness'.