Rafael Cruz did not “flee” like those that were draft dodgers. Rather he left to follow career opportunities in the oil and gas industry.
Why was the elder Rafael Cruz granted asylum by The United States and then become a citizen of Canada? Anyone else would have shown some gratitude to a country that saved his life.
The most reasonable answer is that, as a former Communist Revolutionary that supported young Doctor Fidel Castro, he still despised the evil Capitalist America.