I couldn't read the text in your post (without highlighting) so I'm assuming others can't either. I'm reposting it with black "ink."
Summa Theologica: Part II of book II, question 10, article 11
I answer that, Human government is derived from the Divine government, and should imitate it. Now although God is all-powerful and supremely good, nevertheless He allows certain evils to take place in the universe, which He might prevent, lest, without them, greater goods might be forfeited, or greater evils ensue. Accordingly in human government also, those who are in authority, rightly tolerate certain evils, lest certain goods be lost, or certain greater evils be incurred: thus Augustine says (De Ordine ii, 4): "If you do away with harlots, the world will be convulsed with lust." Hence, though unbelievers sin in their rites, they may be tolerated, either on account of some good that ensues therefrom, or because of some evil avoided. Thus from the fact that the Jews observe their rites, which, of old, foreshadowed the truth of the faith which we hold, there follows this good--that our very enemies bear witness to our faith, and that our faith is represented in a figure, so to speak. For this reason they are tolerated in the observance of their rites.
Divine Providence and The Problem of Evil - St. Augustine
What can be mentioned more sordid, more bereft of decency, or more full of turpitude than prostitutes, procurers, and the other pests of that sort? Remove prostitutes from human affairs, and you will unsettle everything because of lusts; place them in the position of matrons, and you will dishonor these latter by disgrace and ignominy. This class of people is, therefore, by its own mode of life most unchaste in its morals; by the law of order, it is most vile in social condition.