They already did when they voted for him.
It’s true that every individual Catholic who voted for Obama sold out their Church. But my point was that I hope Obama doesn’t find some important publicly known Catholic, such as a bishop, to perform some public function for him. I’m not sure a bishop would dare to do so; what might happen, however, is that some prominent dissident priest, such as McBrien, will agree to serve Obama and the bishops will simply remain silent.