Today's Nullification Crisis

Wait: let me get this straight. It's legally binding for two underlings in the civil rights divisions of the Departments of Education and Justice to send out a “Dear Colleague” letter declaring that, as these bureaucrats interpret Title IX of Congress's Education Amendments of 1972, colleges and universities can't get any federal funding if they don't make special accommodations for transgendered students, however defined; but it is not legal for the president of the United States, pursuant to the Constitution's injunction that he ensure that the laws “be faithfully executed,” to deny some federal funding to cities that declare themselves “sanctuaries” from federal immigration laws, and that accordingly forbid their officials from cooperating with federal authorities in implementing them, as Congress has demanded?