No, he actually does not. Military personnel have curtailed free speech rights, especially while in uniform.
Plus, someone seeking a security clearance while advocating the violent overthrow of the government of the United States (which communists do), then he cannot get a clearance. An officer who cannot get a clearance is largely useless and can be separated from the service. Since he has been given a free education at tax-payer expense, he could be forced to refund the cost of that education, because he cannot fulfill his service obligation.