The problem with Bitcoin is that most of it is bought with Tether Dollars, not "real" Yellen USD. If the US government want to shut Tether down, they will. If they can't find something they are in violation of, they will interpret the laws in such a way that they can be targeted anyway, and even if the Tether Co. wins in the end, they will either get bankrupt in the legal battle and USDT will be worthless.