Friday reread from a perspective of gender philosophy causes cognitive dissonance until you realize that Friday is simply a James Bond type larger than life heroine with all the human foibles that larger than life characters normally display including a tendency to use sex as recreation and manipulation. Put the artificial person Friday in a male case and change the gender of all the other characters and you have a fairly conventional spy thriller, with the hero bedding all the interesting characters of the opposite sex.
Heinlein at least gave a nod to STDs by having Friday immunized and sterilized so that promiscuity which was a designed in characteristic of her artificial personality would not have unwanted results. Heinlein is turning the design aim of female artificial persons as doxies, upside down in Friday's case as she uses her sexuality and sexual favors for manipulation as well as her own gratification. But like a conventional male hero her own sexual gratification is accepted as a integral part of the story line.