To be fair to the other commenter -- this was back in 1962, when Fidel's regime was (elections or no) by all accounts quite popular and broadly supported, and in any case much more legitimate than the regime which preceded it. Meanwhile, the US never had even borderline free elections until some 130 years after its founding (and they were never really quite free until the 1960s). Ironically, by 1962 its elections were still not "free" by modern standards.
Still, "legitimate" is a weird choice of words to describe unnecessary and provocative WMD deployments in any context.
Even by such early point in time, Cuba had already banned free elections. Castro proclaimed in 1961 that "the revolution has no time for elections" and that his dictatorship represents the highest form of democracy. If anyone argues for legitimacy after this point, then they have more faith in the loyality of Cuban people to Castro than he himself apparently had.
Still, "legitimate" is a weird choice of words to describe unnecessary and provocative WMD deployments in any context.