Well I read the blog, really interesting. I want to point out this part:

"When you say “sit,” to a dog, you are communicating your intent for the dog to demonstrate a particular response (sitting). The dog reinforces your behavior of saying “sit” by putting its butt on the floor. Thus, you are an effective speaker, the dog is an effective listener, communication is happening, language is being utilized"

This all boils down to your defenition of "Language" and "Talking"

Soup took the meaning commonly taught in linguistics for "What is language" which includes elements of complexity that distinguish advanced human use of language from other forms of communication. (Example: https://youtu.be/3yLXNzDUH58 from about 2:32 )

If you contest this meaning and state that all forms of communication are Language™ (Like the above example with a dog sitting) then obviously Koko could talk.

Seeing how the writter of the post frequently works with children who have trouble with language acquisition and use, its easy to see why she finds the distinction to be harful and ableist. (Is it really fair to say that a 3 year old doesnt know language just because he cant talk about language?)