SpaceX wouldn’t be allowed to move out of the country. Rocket technology is export controlled under ITAR and a bunch of other federal laws. They would have to have State department permission which I seriously doubt they would get. As far as the offshore barges are concerned I don’t think that would get them out from under the FAA since they would still be a US company. Unfortunately if a government agency wants to control your company you don’t have a lot of options unless you have a lot of support in congress. There is a reason that companies like Boeing and Lockheed spend huge amounts of money on campaign contributions. If they were having a problem like this they would simply make a few phone calls and the FAA would get told to back off from someone very high up. There are still limits to this though as Boeing recently found out.