@Claire1328
Sadly, I think it's highly unlikely that Airbnb CS will remove his review. It doesn't violate the content, nor review policy, not even on the 'relevance' count. That's more when someone writes something that has nothing to do with the listing, e.g. "Traffic is really bad in this town and the restaurants are expensive."
Also, if you read the review policy, it clearly states that Airbnb does not mediate regarding the accuracy of a review. They will most likely tell you that it is "the guest's experience" - their standard response.
If you think it's worth a shot, then go for it. Like you said, you've got nothing to lose.
In terms of the response, I get what you are saying RE AirReview, which is something that I also use, but I would absolutely not post that response if I was you. While a few hosts might see it (from what I've read here on the CC, most hosts don't even know about it, let alone use it), your potential future guests will and that is the audience you should have in mind when writing a response.
Those guests can't see the star ratings this guy left and his review doesn't say anything negative. It is surrounded by lots of good reviews, so doesn't really stand out, and will soon be buried under more.
I know the rating really hurts, especially when it scuppers your chances of Superhost this assessment, but you will get achieve it as, luckily, as long as you vet guests, this type of low scorer doesn't come across too often. I would definitely just let it go and not respond.