That is the only way it is legal. This was an export directive from the Commerce department, using authority granted by Congress to control exports of tech. If they just told Anthropic to shut down a model without invoking an emergency order of export, there would be no legal authority for such an order.

Keep in mind that for all the troubles and trauma caused by the current USA government, they are really good at manipulating the legal system to get their way. This is just another example of it.