His arguments against the "systems response" have to stand or fall on their own. The Chinese room doesn't have anything to add. If the "systems response" fails, then we already know a computer can't be conscious without any additional thought experiments.
Lastly, I think he goes much too far in dispelling the mystery of the word "computer". As Dennett and others have pointed out, a working chinese room that displayed clear signs of consciousness would be an artifact far beyond current human comprehension, either in scale or sophistification or both. Searle asks you to imagine a human taking slips of paper and calmly consulting a rule book and producing new slips of paper, and claims that it is "obvious" that this system can't be conscious. Well, I agree, but it's equally obvious that the system couldn't possibly display conscious-seeming behavior.
The best defense of the CR that I've heard is that it is only intended to prove that a _purely formal_ system (i.e. GOFAI) can't be conscious. I find this more plausible, but I still don't think the CR adds anything to that argument. And, to reiterate the previous paragraph, I think if you had a formal system that everyone agreed _seemed_ conscious, it would be such a complex artifact that it wouldn't be obviously unconscious in the way that, say, an eliza bot is.
The question Searle is raising with the thought experiment is where the understanding of Chinese is happening. It's clear that the understanding is not happening with the homunculus. But if not there, then where is it happening? Some functionalists responded with the "systems response" which is that the system of the room plus the homunculus is what has the understanding even though no element of the system taken individually has understanding. He goes through a pretty detailed reply to the systems response, but the basic argument against it is that it's incoherent. There's no well defined thing that is the system. You can remove the man from the room and put him under a tent in a field. Where does the system end and the rest of the world begin?
You are of course correct that the experiment can be reformulated without the human, but that's exactly the point. A computer is mechanistically doing exactly the same thing as the man in the room. But if the man has no understanding and the room has no understanding and the system has no understanding, removing the human from the equation changes nothing. The reason Searle included the human is because saying "computer" invokes a lot of mystery to a lot of people as to what's going on. But a computer is doing nothing different than the man in the room.