It’s a rhetorical answer to a rhetorical question, not what the author actually believes Satansburg would look like.
The point is, without Christ, what’s the point of leading a squeaky-clean, G-rated lifestyle? To prolong everybody’s march to the grave? People who don’t appreciate the true heart of the Gospel—Jesus’ saving power, the prospect of eternal life with God—and mistake all the “dos” and “don’ts” for its central message avoid sin not out of their faith in Jesus, not in an effort to make their lives a tribute to God’s goodness, but just so they can feel good about themselves. Works without faith are dead, too.
The motivation is pride. If you sincerely believe that doing these things makes you a superior person, then that is justification enough for doing them.
Satan doesn’t care how he gets you, claiming you to pride is more than enough for him.
This is why the real Christian knows in his heart that he is scum, and that these sinful desires lurk around the corner, and that he needs Christ because he cannot do it on his own.