As an update, I might add that the window has effectively eliminated unseen sexual interactions inside the sauna and made room for another, more open form of sex between people on either side of the window: exhibitionism and voyeurism.
Exhibitionism and voyeurism don't transmit HIV, herpes, syphillis and other monsters in the sexually transmitted disease zoo. This is a simple matter of public health.
A guy with a Ph.D. ought to be able to understand this.
As a side note, I remember sometime back in the 80's that several 'bath houseses' in Toledo were closed down by the Dept. of Health after they found a very elevated sperm count in the water.