Creon wasn't a run-of-the-mill tyrant -- he was a respected monarch who put the good of the city over moral/religious concerns.
His dispute with Antigone is about law vs personal/religious ethics, not about him being a capricious tyrant (besides in the end he relents). Her brother was a traitor.
As long as the inhabitants agree on a specific course of things and have found them to help the city, the "good of the city" as concerning its government is meant as just following that.
So, "good of the city" as in "doing what the city deems good", not as in moral.
Such a capriciously specific command makes it sound like you'd be more of a run-of-the-mill tyrant à la Creon.