He sounds a bit conservative to me as though he was upset about the changes the country was going through. He wanted things to stay like they were in the 1940's and 50's. What he seems to think of as an innocent age but I would say it was far from an age of innocence and the 60's and 70's was an awakening with protestors and MLK Jr. inspiring millions. Kind of reminds me of the movie Pleasantville. He wanted things to stay black and white but people were screaming for their own identity and equal rights and fairness.
Washington Post: Gloomy Don McLean reveals meaning of American Pie and sells lyrics for $1.2 million
Snip:
People ask me if I left the lyrics open to ambiguity, McLean said in an early interview, as the Guardian reported. Of course I did. I wanted to make a whole series of complex statements. The lyrics had to do with the state of society at the time.
But what state was that? It seemed like the songs cast of characters which include a jester, a king, a queen, good ol boys drinking whiskey and rye as well as Miss American Pie herself were meant to represent real people. The song includes references to Karl Marx; Vladimir Ilyich Lenin (or, more likely, John Lennon); the Fab Four; the Byrds; James Dean; Charles Manson; the Rolling Stones; the widowed bride, Jackie Kennedy; and the Vietnam War.
What does it all mean? Just what a song about the day the music died seems like it might be about: the end of the American Dream.
Basically in American Pie, things are heading in the wrong direction, he told Christies, as the Newcastle Herald reported. It is becoming less idyllic. I dont know whether you consider that wrong or right but it is a morality song in a sense.
Link:
https://www.washingtonpost.com/news/morning-mix/wp/2015/04/08/gloomy-don-mclean-reveals-meaning-of-american-pie-and-sells-lyrics-for-1-2-million/?utm_term=.39cab921b1f6