The U.S. government could speak openly and directly about what is going on in Bahrain, and the sky wouldn't fall. But it might be "inconvenient." So the U.S. government is not going to speak openly and directly, unless there is some real public pressure.
The question is why the United States was even thinking of selling arms to Bahrain. The answer can be found in the fact that the United States is the number one arms supplier in the world and to maintain its status it cannot be judgmental about the conduct of its customers.