The author points out a lot of the contradictions in the propagandists' myths regarding WWII, but appears to be rather confused about "what we're up against". It is a tribute to the Empire's propagandists that Americans on the left still don't know, more than 65 years later, what WWII was really about. His emphasis on racism throughout the article is only slightly offset near the end by including Zinn's question which only vaguely suggests another reason for the war.
"Was it a 'mistake' or was it an action to be expected from a nation with a long history of racism and which was fighting a war, not to end racism, but to retain the fundamentals of the American system?"Zinn's feeble question implying something about the American system is not very helpful. The "fundamentals of the American system" that Zinn refers to here is not American at all. It is largely a product of Western civilization. In this statement he is timidly referring to capitalism.
With regard to racism, ruling classes learned a long time ago that if one divides enemies into warring camps, it is so much easier to maintain their rule. This "divide and conquer or rule" strategy has been used with great success by ruling classes throughout history, and it continues to be used today. Racism in 1930s Germany was also a very useful way to deflect all resentments about an oppressive capitalist economy onto Jews and gypsies along with other groups such as communists who were often equated with Jews. Today's Empire propagandists prefer to target "terrorists" and equate them with Muslims.
American leftists really need to be de-programmed in order to rid themselves of so many false and misleading ideas implanted in their heads by American institutions. The only way to do that is to read books from independent sources. Only reading books by Zinn will not suffice. Zinn's material is only for beginners. Regarding WWII and American capitalism I suggest reading such books as Facts and Fascism by George Seldes, Trading with the Enemy by Charles Higham, Triumphant Plutocracy by R.F. Pettigrew, and others listed on the books section of this blog. (Pettigrew wrote his book in 1921 after serving two terms in the US Senate and other government posts. That's right! In 1921 he already knew that the US was a plutocracy--something which many American leftists today, nearly 100 years later, are just discovering.)
Basically what WWII--and this was only "part 2" of WWI--was about was a contest between Anglo-American and German-lead capitalist empires for world dominance. See this for more on my views about WWII and this recent article by Dr. Jacques R. Pauwels.