This is a very thorny question. How do we assess the committment to bourgeois democracy on the part of the US ruling class? Structural changes in Japan and West Germany after WWII would seem to represent a "completion" of the bourgeois democratic revolution as the authoritarian traces of the Mikado and the Junkers were eliminated under US bayonets. One can almost imagine the CPUSA hailing the "revolutionary" American bourgeoisie playing the same kind of role in these countries as the victorious north played in the defeated Confederacy.
The problem, however, is that the American imperialists have not acted in a consistent fashion. If it had supported the goals of the bourgeois-democratic revolution in China or Vietnam, then its behavior in Japan and West Germany might seem more credible. In reality, Ho Chi Minh's appeal to the principles of Jeffersonian democracy fell on deaf ears as the US supported France's bid to retain control of its colonies and prolong landlordism in the countryside.
I have very little confidence in the morality of the US ruling class, which I think is capable of horrors beyond Hitler's imagination. After all, the German ruling class--despite Goldhagen's remonstrances--only turned to fascism as a last alternative. There is plenty of evidence that Social Democracy and German capitalism were quite compatible, Kaiser Wilhelm's support of social legislation before WWI a case in point.
Under the very slightest pressures, the US ruling class introduced McCarthyism. Imagine what this country would look like if it had lost a major war, and the unemployment and inflation rates were the same as Germany's in the 1920s. I am quite sure that Fortune 500 companies wouldn't think twice about backing war and genocide.