But I think perhaps you've missed his subtle use of language.
Fish swim, obviously. What submarines do in water isn't usually described a swimming.
That's a bit odd in when you think about it as in both cases the objective is to get from A to B, while in the water. In fact if you look at only the outcomes, what fish and submarines do when swimming looks almost identical. They move (or perhaps be stationary in a current), they tend to be efficient about it, they try to not make a lot of noise, they even use very similar mechanisms to move vertically.
Despite that it almost seems that to swim you have to be fish, or a sea snake, or a blue bottle or water bug - but not a submarine. And going by the discussions here to think you have to be a human, or a dog, or just about anything but a computer. And that's true no matter how closely a computer can emulate tasks we say require thinking in a human.
A conclusion you might draw then is whether a submarine swims deciding belongs in the domain of linguistics, not computer science. And he's saying that's true for whether computers "think" too.