It’s not about the rapist, it’s about getting the mentally-challenged daughter fixed up so that a rapist, or her own behavior, won’t get her pregnant. That way, if their mentally-challenged woman won’t show the signs that sexual abuse happened, to give the impression that it didn’t happen.
I was trying to point out the illogic: “...we worry that they will be sexually assaulted, so we prefer to cut out their wombs.”