I think bittrex is legally obligated to do this, due to the relations US has with some of these countries &(it's residents).
So, unless you are from one of these countries, i don't think there is much to worry about in this case. It isn't MtGox.
They can easily figure out who each country is registering from. Why do they confirm the identity of these people? So we conclude that if a corrupt government came to power in a country, we would let the people of that country be plundered. The oppression again against the oppressed people. with this method Surely the world will be corrected .
You somehow indeed have a point. I don't get why they would people like OP register in the first place if these countries were indeed banned.
Could be that legislation changed, or that they are not necessary banned, but just taken under a loop, and verified that the coins of him are clean.