I didn't say yes. I can say no to anything I say vile, and I don't have to count the cost. But because you said yes, all that you can do, for all your crown and your trappings, and your guards—all that your can do is to have me killed.
The political heroism in Antigone's resistance is her refusal of state power. Antigone says no to all she finds vile, and in this sense she is more powerful than the ruler beholden to his throne. Despite all his trappings of power, Creon finds himself helpless, unable to act on his own. He wants not to execute Antigone but cannot help ordering her death. Having said yes to state power, he is circumscribed by his own kingship, by very the throne that makes him the master of the land. He has surrendered himself entirely to the state and knows his circumscription all too well. Unlike Antigone, he has completely ceded his desires to take upon the mantle of governance. Creon is rendered loathsome, terrified of what his office requires of him and yet unable to act otherwise.