I think when the negative focus is on the disability, that's when it's disablist.
Somebody on here felt a colleague wasn't working well because of personal issues at home, and that management hadn't handled it well. Fine. But it instead became a diatribe about all the things he apparently needs due to DD's disability, when really that part was not relevant, and not any of the OP's business.
Similarly on another thread a while back someone felt they had the right to march into a headteachers office and ask what was being "done" about an SN child. Literally none of their business. When the real question was "AIBU unreasonable to think the balance of SN provision in mainstream is poor?"
YANVU says THE ENTIRE WORLD but YABU to fixate on an individual child and believe you have ANY entitlement whatsoever to know their tatement/EHCP just because your child is in the same class. Disablist.
From a personal stand point:
Hi I'm Song, I like books and jigsaws and Game Of Thrones, I've got friends, I've got loved ones and experience the same relationship issues as all women. I work. I have hobbies. I am not internally different from the next woman. I use a wheelchair. I am repeatedly penalised for that for no reason, like struggling to get into the bar my book club is in, or people looking at or addressing another person when talking about or to me, before actually seeing if I am able to communicate. My disability is secondary and being treated as if it's all I am gets right on my tits.
In adulthood my biggest problem has been employment. Employers are very, very reluctant to employ disabled people and almost every disabled person I know with a job inc. me work in some kind of disability/health related position - it's what I have but it is not who I am and I don't really want to spend my life educating people about courtesy over things that should be blindingly obvious ie you wouldn't speak to someone with a baby voice because they had the flu so why would you talk like that to an adult with Downs?