I would say simply that Romans doesn't exist in a vacuum. So when Paul wrote Romans 13, was there an example he was referencing? Was Rome a terror to Christians or a blessing? Jesus did what was good, so did He receive the approval of the state? I believe that Jesus has all authority in heaven and on earth. I think Paul believed that as well; he was familiar with the Old Testament and what had happened to Samuel—how Israel had rejected God as their ruler. Isn't that exactly what Christians do when they follow the godless and throw in their lot with sinners?