This is Horowitz at his slickest. He doesn't mention why all that changed in 1947.
The answer is simple: Republicans won a landslide election in 1946 even greater and more unnerving to the liberal establishment than the GOP victory in 1994.
Coulter points out in Treason that Truman turned anticommunist for the same reason Clinton signed Welfare reform: the American people had spoken and taken away control of Congress from the Democratic Party.