Dear Noson,
I can't agree with your argument quite as you put it, but I think you're on the right track. I like the premise "that the universe is chaotic and lacks structure," and that something "acts like a sieve" to pull out only the very small subset of phenomena we actually observe. But as you note, it hardly seems reasonable to make scientists the primary agency of the selection process. I would rather say that science involves the discovery of nature's own selection rules, which are complex and operate on many levels.
You say at the start - "These laws of nature are fine-tuned to bring about life, and in particular, intelligent life." Well, they are evidently fine-tuned, and they do support life, but I argue in my essay that the structure of the physical world makes the emergence of life exceeding difficult. And while biological evolution did eventually produce quite intelligent animals, the leap to our human kind of intelligence hardly looks to be preordained in the selective principles of biology, much less in the laws of physics. This entire history looks much more like a series of unlikely accidents than something built into the structure of the universe from the start.
My suggestion is that physics itself provides the "sieve" - specifically, in the complex system of recursive processes that scientists make use of when they observe and measure things. We humans aren't responsible for the fact that physics has a complicated set of symmetries that can make all its components empirically observable. Nor is this something the universe does just for the sake of intelligent observers.
I argue that in order for any kind of information to be meaningfully definable or communicable, there always needs to be a context consisting of other definable and communicable information. The physical world clearly provides such contexts... that is, the observable universe consists of the subset of structureless chaos that not only has structure, but succeeds in defining all its own structure and communicating it interactively. This is the source of the predictability of phenomena, and the many kinds of symmetry that make it work - which we observers take advantage of for our own ends.
In any case, I appreciate your imaginative line of thought here and the clarity of your writing.
Thanks - Conrad