If I were to publish a boomer shooter, where you can see low-poly bodies of innocent adults being tortured by monsters or machines, would that be against the rules?  We are talking about all kinds of very creative and very brutal torture here, but always low-poly 3D models.

If you're not doing it for the shock value or controversy, it should be acceptable under the itch.io terms. But maybe add a content warning to your game page.