I think you’re right about services for disabled couples.
But I suspect for many group homes for the mentally retarded, things are much easier to handle if they are single-sex.
It’s good to have a variety of things for a variety of people, but not to force everything to be for everyone.
Mental retardation can come long after birth. It can happen at any point between birth and death such as a traumatic head injury {in adults}, excessive prolonged fever in childhood or adulthood, etc.
There's several things going on. One thing is kids who are born with mental retardation who sometimes did not live to puberty are being helped and the same with head trauma patients. Much of it depends upon the persons capacity. There are certainly mentally retarded persons who can and should be allowed to marry. If we say no to them then do we say no to persons with physical disabilities for the same reasons? Force divorce?
I've worked in health care facilities which did have some developmental impaired patients both from birth and accidents most of them could had they been allowed to married. Should elderly patients with onset of Dementia be separated? One building at the facility I worked in was a barracks type of set up. The building was basically for persons whom the state had booted from a nearby mental institute years before but could not take care of themselves. The men were in one wing the women in another. A few more were in patient rooms in another part of the facility.
This may sound like B.S. to you but the patients in nursing homes etc do engage in sexual activity with each other sometimes. Just ask anyone who has worked in one and they can tell you. By law unless it is a forced act the employees can not interfere.