This verse from the Narada Smriti permits sex with promiscuous women, prostitutes, and unmarried women freely:
12.78 - Intercourse is permitted with a wanton woman, who belongs to another than the Brahmana caste, or a prostitute, or a female slave, or a female not restrained by her master, if these women belong to a lower caste than oneself; but with a woman of superior caste, intercourse is prohibited.
Narada is understood to be an incarnation of Vishnu. This means that Vishnu permits men to have sex with prostitutes, promiscuous girls, unmarried women, and female slaves.
But first, is this an authentic verse spoken by Narada Rishi himself?
According to the footnote for that verse on sacred-texts.com, there were many medieval commentators for that verse, namely, Madhvacharya, Vigñânesvara, Mita Misra, Viśvanātha, and others.
My question is, can someone provide an English commentary for that verse, or an English translation of the Sanskrit commentary for that verse?