Umm......well, for starters I don't understand the part where you claimed "When AC tells the USA a USA citizen without permission is trying to fly to Cuba.....".

Here are the parts that you don't seem to understand. AC doesn't know whether a U.S. citizen does or doesn't have U.S. government permission to travel to Cuba, does not ask its passengers whether they have U.S. government permission to travel to Cuba, and would have no way of verifying whether a traveller had U.S. government permission since there's no documentation, paperwork or record keeping of legal travel to Cuba by Americans in most cases. AC is not asked and does not report to the U.S. government whether its passengers have U.S. government permission to travel to Cuba. Finally, as has also been pointed out on this thread, there is actually no specific prohibition on travel to Cuba by U.S. citizens. What the U.S. government prohibits most of its citizens and green card holders from doing is spending money in Cuba.