Do you think Rubio is a dual citizen?
In October 2011, newspapers reported that Rubio's previous statements that his parents were forced to leave Cuba in 1959, after Fidel Castro came to power, were embellishments. His parents actually left Cuba in 1956, during the dictatorship of Fulgencio Batista. According to The Washington Post, many voters in Florida would be less impressed by his family being economic migrants instead of political refugees from a communist regime. Rubio responded, saying: "The essence of my family story is why they came to America in the first place, and why they had to stay."
So Rubio's parents were not political refugees, suggesting that Cuba would not have revoked his parents' right to descend citizenship. That isn't to say that Cuba didn't do this later when Rubio became an American politician.
It may simply be a case similar to Cruz' of Rubio not knowing of a Cuban citizenship, if there was one.
-PJ