"Who the hell is going to care for him?????? No employer will hire him, no normal girl is going to marry/love him and you are not going to live forever!! Personally, they should take whatever non retarded body parts he possesses and donate it to science." The anonymous author added, "... you had a retarded kid, deal with it... properly!!!!!"
As offensive as this letter is, the author does have a point - of sorts. In a survival-of-the-fittest, individually-competitive world with no assistive technology, no social services, no civilization of any kind, this autistic boy wouldn't have a chance. Nor, of course, would anyone with a host of conditions ranging from blindness to asthma to schizophrenia to albinism.
That's the way biological evolution works - that which is fit (or lucky) survives to pass on its genes. There's a whole world view dedicated to this kind of approach; people should come with skills in place, no training required. If you can't fend for yourself, you're not meant to survive. If you're different (i.e. difficult) in any way, you don't belong. The traditional ways are best and aggressive competition is the only way to produce solid results. This system buys in to the myth of humanity on a downward spiral from a fictitious past where we were free of disease, illness and the ravages of nature.
Of course, that's not how our world works. We don't grow our own food, manage our own health, fix our own cars, etc, etc; we are a system, not a series of silos, entirely dependent on the health of the whole to maintain the well-being of the individual.
Every human society (and many other species, as well) includes empathetic, altruistic institutions. Society relies on The Golden Rule, which is why it's universal. You literally cannot have a dense concentration of people without an imperative to love your neighbour; otherwise you'd be removing anyone who got on your nerves - including those hyper-sensitive, anxious folk who present as bigots.
It's a good thing, too - without those "special needs" folk, our society wouldn't be possible. Despite what free-market purists like to tell us, innovation isn't about making money - it's about solving problems. Often enough, it's those so-called "problem people" who think outside the box (sometimes on scales incomprehensible to "normal people") or connect the dots in ways that elude the majority.
In fact, despite what the anonymous neighbour tried to tell Karla Begley, there's a growing market for innovation and new approaches - as a result, the sorts of people who come up with them could do quite well.
People like Jacob Barnett.
Or Stephen Hawking.
Whether it's a hate crime or not, the Anonymous Neighbour's letter is absolutely a crime of reactive ignorance. Social evolution is rapidly replacing biological evolution - collaboration, acceptance and education are more valuable skills than self-reliance, aggressiveness and the like. You can dislike the trend, but it's a well-established one.
My suggestion would be this - if the Anonymous Neighbour is so set against committing sociology, a hermit's life might be a better fit for them. I would, however, certainly not advocate suicide - to deny the rest of us of their problem to solve would be a crime against society.