This is pretty much it, and it's a really subtle detail that causes a lot of confusion. This is why the real problem with Maxwell's demon isn't how you obtain the information, it's how you store the information, as Landauer showed. To extract useful work you have to erase bits ('forget' knowledge) at some point. And this raises the entropy.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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