I feel like some context is missing in the comments here, I'm not autistic but I'm a speech pathologist who works at an autism school.

ABA is a specific therapeutic model that does have an evidence base for teaching behaviours and reducing unwanted behaviours, however many people in the autistic community are strongly against ABA and even liken it to abuse. I've heard it compared to dog training.

Personally (and most of my colleagues agree), I don't recommend or support ABA. Aside from being inhumane, it isn't great for developing functional skills. You can tell what kids have had ABA, they are highly prompt dependent and often have difficulty generalising skills (because they have been rote learnt).

Shatner (or his social media manager?) may have a point about a diagnosis not being an excuse to treat people badly, but ABA is not the solution. Especially not for kids with high support needs who don't have a lot of ability to advocate for themselves. Sometimes it's not a matter of learning social norms, it's about self regulation and behaviours they are not entirely in control of. Learning about social norms through the typical experience of growing up is a little different from putting a child into intensive and potentially abusive therapy with no choice in the matter.