I assumed the rape machine production line cleaning would have been automated?
"Oh, no, I do understand, but I have no choice. There just is not enough time left."
Caretaker worked out that he could cycle through more aliens, and maybe make a baby, if he redacted the janitor droids and turned off the automatic steam scrubbers inbetween mass rapes.
Which is only a little worse than one of us using the same condom for a month.