If you knew anything about autism you might know how routinal they can be, for example, maybe the child want to play on his trampoline every day at a certain time, whether it's sunny, rainy or even -20, they don't care, they have to do it. and regardless, why can't a child play out in his garden? my neighbours kids aren't disabled in any way, but when they play out on their trampoline they scream and shout and laugh and are very noisy, but I don't complain, it's what kids do, let them enjoy themselves. a non verbal autistic child is not easy to look after, if he is screeching with joy or sadness or whatever, it is a good thing, he is communicating, and hopefully he can develop with his communication. would you rather he be forced to stay inside, never socialize and have no chance of a life whatsoever?
It's not about what I may or may not know about autism fella, it's about being decent neighbours. Of course a child should be allowed to play out in the garden but if he weren't autistic and just made a general racket by squealing all the time then a decent, neighbourly parent would nip it in the bud after a while. I know all about how difficult it can be for parents of children with autism but that doesn't mean they can't try to be good neighbours by showing some consideration for those in the immediate vicinity who appreciate a nice quiet hour in their own garden.
You can twist what I say in order to imply I'm selfish/heartless etc but rest assured that's not the case, I already said she seemed a nice woman, the story wasn't about her autistic boy, it was about the anonymous letter and I've already said it's not what I would have done but if I lived next door to her I may well try and negotiate some quiet time when the trampoline is closed 'for maintenance', being a considerate neighbour myself I'd be fairly confident of coming to an amicable loose fitting arrangement that would suit us all.