Yeah this is the problem with this shit. They come out the gate with the "it's problematic because it hurts deaf people" argument that is pretty much indefensible. The rest of it while a rant does contain a lot of legitimate criticisms of a study that while I'd not say is utterly without value is nothing like the popular perception of the case.

Gorillas aren't stupid but they aren't smart enough to he taught human language signed or not. You can similarly train your dog to "ask you" for food. Same with a cat.

The animals figure out that whatever action means you give them food and they go for the pavlovian response there.