I've read the first part of the post ("What is Speciesism?"), and have a question.

Does your argument have any answer to applying modus tollens to the argument from marginal cases?

In other words, if I say: "Actually, I think it's ok to kill/torture human newborns/infants; I don't consider them to be morally relevant[1]" (likewise severely mentally disabled adults, likewise (some? most?) other marginal cases) — do you still expect your argument to sway me in any way? Or no?

[1] Note that I can still be in favor of laws that prohibit infanticide, for game-theoretic reasons. (For instance, because birth makes a good bright line, as does the species divide. The details of effective policy and optimal criminal justice laws are an interesting conversation to have but not of any great relevance to the moral debate.)

Edit: Having now read the rest of your post, I see that you... sort-of address this point. But to be honest, I don't think you take the opposing position very seriously; I get the sense that you've constructed arguments that you think someone on the opposite side would make, if they held exactly your views in everything except, inexplicably, this one area, and these arguments you then knock down. In short, while I am very much in favor of having this discussion and think that this post is a good idea... I don't think your argument passes the ideological Turing test. I would have preferred for you to, at least, directly address the challenges in this post.