As the saying goes, "ignorance can be fixed but stupidity is forever". Therefore, I think the author is wrong and he is using the term "stupidity" where "ignorance" would be way more appropriate. As the article says, "Political scientists and other researchers have repeatedly documented that the American public does not have a sophisticated knowledge on political matters. The average American also does not use a coherent and consistent political ideology to make voting decisions." To me this is political ignorance or lack of political education, but not stupidity.