While yes, I am under no illusions that some parents refuse all offers of help etc, it didn't seem like that in this case, and I think that given the right support, MAYBE there could have been a better outcome.
And saying that there was only a '6 month window' for the child's SN to improve is frankly insulting to those of us who have a dc with SN that are making daily improvements right up to the time they are adults. My 13yo DD, despite EVERY bit of help that she was given at primary, was unable to read or do simple mathematics beyond a reception level ('p' scales) at the end of Y6. Yet less than 3 years later, in Y9, she is working on NC lvl 5 in most subjects, and got a 'C' in her mock RE GCSE paper. Some children with SN bloom when they are older, despite all support put in place when they are young.
Though, I WILL admit - if they DID turn down speech therapy for their child, then something IS very wrong. My DD was on the waiting list from the age of 18 months and she didn't get her first appointment until she was almost 3yo. I would have bitten the arms off anyone who offered to get her an appointment sooner!
My DS1 is fine, working on 11+ prep right now, no problems other than being coeliac.
My DS2 ALSO has the same problems as my DD (well, some of them).
My DS3? Developing perfectly normally.
NOT environmental SN.
I'm NOT trying to make excuses, or say that the household wasn't neglectful - but my own situation illustrates that even those that have NO parenting skills due to their upbringing can be taught how to parent effectively.