Furthermore, even those contrived laws don't generally claim it's cruel to eat animals. Bringing up the fact that religions oppose animal cruelty is like pointing out that every religion and culture has rules about sexual immorality, and therefore we should oppose some particular type of sexual immorality that you don't like.

Actually, he's responding to PG, who claimed that no major religion is against cruelty to animals ... presumably implying that this is a modern aberration? Or something? Regardless, it was he who claimed (in your analogy) that since no religion is against "sexual immorality", then clearly modern dislike of rape is not a part of basic human ethics.

During much of history, most cultures that knew Jews attached zero or negative utility to them, but pogroms only happened every so often. They didn't just kill all the Jews until the Nazi era.

They demonized them. That is not the same as attaching "zero or negative utility" except in the most dire of cases (which, admittedly, crop up with some regularity.)