This doesn’t happen often, but I’m with Marc Ambinder.
Federalism is a technique of political organization, not a free-standing moral principle. “That ought to be decided locally” is not an adequate answer to the question “What’s your position about X?” unless the right thing to do about X genuinely varies from place to place. And even then, you ought to say why: Montana is less crowded than Manhattan, and needs fewer noise-restriction laws.
When X is a matter of simple right and wrong, then it may still be right to say “X ought to be decided locally,” or “The Constitution assigns the decision about X to the states,” but that alone is not enough. You also ought to say where you stand personally. The Constitution leaves most of the criminal law to the states; but if a state chose to decriminalize child-molesting, I’d expect public officials everywhere to join with citizens in denouncing that as a wrong choice.