This is not an isolated incident - A large portion of the population legitimately believes that allowing people with learning disabilities to live and breed will lead to negative outcomes for all involved, including the disabled.
I do not want to kill, or even order mistreatment. I want everyone, regardless of their abilities or disabilities, to live long, healthy, productive and fulfilling lives. I'm not going to pretend that we're anywhere near that point, nor that I think we can achieve that if we declare ourselves there too soon. We need to, as a society, be working towards accomplishment and achievement, and there are classes of people who are a net drain. We are human, and we can do our best to make life comfortable for them, and to attempt to reduce that drain, but we cannot allow such time and money sinks to grow unbounded.
And yes, part of that is flat our eugenics - Making certain that Downs Syndrome and other serious developmental disabilities are caught in the womb and aborted early. The pain of an early abortion and the possibility of everything working out alright (as it has for a small percentage of persons with downs syndrome) are not, on balance, worse than seeing my cousin figure out that she will never learn how to drive, that she'll never have a job, and of her mother, who is afraid she will die before her daughter and leave her to a world that cannot care for her (and already doesn't, and never will).
Call me hitler, but I'd rather put down a wounded animal than watch it suffer in pain that it will never escape - and while the calculus is different, humans are animals, too.