Please show me one grocery store where you can buy imitation human meat. Or ten strangers on the street who'd be OK with it compared to those who'd be OK with imitation animal meat. It is absolutely not acceptable.
The reason we don't have it is not due to morality, it's due to not needing to since we have other foods. And either way it's not actual human flesh, it's simply a substitute. You could make the argument that anything could be a human meat substitute, since animal meat is not much different from human meat, and as such, animal meat substitutes would also be human meat substitutes.