I don't think there is a big enough market for wild cuban cichlids for there to be any exporting done. Anyone who wishes to start a business doing so would not last very long. Most, if not all of the wild cuban cichlids that have entered the US were most likely brought in by a hobbyist or scientist for personal purposes.
The embargo on Cuba has been in place for almost 50 years! When did Cubans first take to the scene? I don't mean when were they discovered or observed, but when were they actually considered a sought after ornamental fish? For the most part there wasn't too much interest in CA/SA cichlids until the 80's, so technically speaking they should never have entered the country, if there is no way of getting them in.
Also, you don't have to personally bring the fish into the US. There's this amazing thing called international shipping, in which you can ship to and from places like Canada and Europe. Cubans are not illegal in the US! And as long as the fish weren't "purchased" in/from Cuba(ie. European tourist/ hobbyist catches a box full and brings them back with him), someone from Europe, or Canada would have no problem selling/shipping them to the US. But like I said before, there really isn't a big market for these fish, and especially to purchase them wild caught. Most people, including myself, would not go through the trouble(mainly $$) to get wild cubans. So if, and when they do find themselves in the US, I can promise you, there will not be enough of them to raise any flags, anywhere. If there was that much business in Cuban cichlids, I'm sure the US would be more than happy to add them to the list of illegal species.
Now, DOW, I don't think your question was whether these fish can get into the US, but rather questioning whether the OP of the other thread's fish are truly wild. This I cannot answer, nor do I really care. But I think we can agree that if someone truly want's to get these fish wild, it wouldn't be extremely hard to do.