Oh, no worries: the other site where the unauthorized distribution took place - believe it or not - just so happens to be the official community forum of the game engine the asset is tailored to. I’ve already made their staff aware, and the link was taken down + the user contacted. I’ve made sure to document everything beforehand, of course.
This doesn’t mean however that it should be tolerated having known thieves on itch.io - if there’s proof that someone (who even develops and offers stuff on here themselves) is pirating other people’s works, I understand that there’s not much itch can do about the distribution aspect itself… but what they can do is to ensure the user cannot engage in any further illegal activity via this platform. It is, after all, a clear and severe violation of ToS.
Again, support has been contacted now. Thanks for sharing your opinion.