The core objection I'd have to your argument: humans also don't have privileged access to the territory. Neurons don't have some metaphysical super power that let them reach into the True Reality; all there are are maps encoded in our neural circuitry by learning rules that evolution has developed because those learned maps lead to greater reproductive success. If direct access to reality is what's needed, then it's true that machines are incapable of thinking; but then so are humans.

I happen to agree with your assertions. I entertain you conclusion as a distinct possibility.

Maybe we aren't? :)