I'm not suggesting Bryant has the authority to do anything unilaterally. He can get behind bills that essentially "nullify" federal law that is unconstitutional. The Sepremacy Clause you reference does not mean the feds can pass any law they want and the states have to deal with it "like it or not". The Federal government cannot exercise any power not deemed to it by the Constitution. The Constitution is a document that limits federal power, not states power. The 2nd amendment is clear, it shall not be infringed upon. The Supremecy Clause is only applicable when the federal law is within the confines of the Constitution. James Iredell, at the First North Carolina convention: “When Congress passes a law consistent with the Constitution, it is to be binding on the people. If Congress, under pretense of executing one power, should, in fact, usurp another, they will violate the Constitution.” Alexander Hamilton, at New York’s convention: “I maintain that the word supreme imports no more than this — that the Constitution, and laws made in pursuance thereof, cannot be controlled or defeated by any other law. The acts of the United States, therefore, will be absolutely obligatory as to all the proper objects and powers of the general government…but the laws of Congress are restricted to a certain sphere (Constitution), and when they depart from this sphere, they are no longer supreme or binding”.
The Meredith/Barnett situation is different. James Meredith wasn't admitted to Ole Miss because he was black. The Supreme Court ruled that Meredith had the right to be admitted because he met admission requirements. Barnett tried to get the State Legislature to change the requirements for admission that would have blocked Meredith. Thank goodness he had no traction with this because it probably would have worked but the pressure was too high on Barnett at that point and he backed off.