I'd hate to moralfag but I believe there are certain things that are past the point of no return and absolutely repulsive that regardless of who does it, deserves what happens to them
A person raping their own mother, one that's elderly and can't fight back at that along with being mentally ill, would likely be grounds for public execution in the old days and I don't think anyone would protest it
If a mentally handicap person does something fucked up, then there's no telling when they'll do it again and should be dealt with as soon as possible.