Your cat was already capable cognition before you started training it. GP is talking about generating a cognition where it did not previously exist.

Why couldn't a mechanism (say A Neural Turing or whatever) that you train be "cognition capable" when you start and then be trained to actual behavior after that?

You would need something that is "cognition capable" first and that has not been invented yet.

It's hard to know. Maybe something "cognition cable" exists, it's just the proper train routine hasn't been provided to it.

But regardless, the broader point is yeah, combine something akin cognition capability and the proper training routine and there you go, AGI from "reinforcement learning", broadly defined.

Also a layman, but I think OPs point wasn't that it isn't possible, but that's it's not effective or analogous to how humans or other species learn.

For example, your cat's brain isn't just a randomly initialised neural net. Your cat comes pre-wired in such a way that it understands certain things about its environment and has certain innate biases that allow you to train it to do simple tricks with relative ease through a reward mechanism.

A more analogous example would be building a cat-like robot with four legs and a neural processor then switching it on and expecting to be able to train it with treats. Without a useful initial neural state (founded with an understanding of cognitive psychology and neuroscience) it would be almost totally useless.