The most likely reason for scrapping the program so thoroughly was to benefit the US aerospace industry; they wanted to ensure there was no chance of competition, and encouraged the notion that ICBMs had made interceptors obsolete, as an excuse: https://nationalpost.com/news/canada/canadas-avro-arrow-jet-...
After this news broke there was, briefly, a campaign to convince the government to consider revisiting the Arrow, but it was rebuffed on the grounds that it was rather unstealthy: https://www.autoevolution.com/news/one-decade-ago-canada-alm...
The most likely reason for scrapping the program so thoroughly was to benefit the US aerospace industry; they wanted to ensure there was no chance of competition, and encouraged the notion that ICBMs had made interceptors obsolete, as an excuse: https://nationalpost.com/news/canada/canadas-avro-arrow-jet-...