No, I don't it has anything to do with copyrights, there's a different procedure for that. As for reviewing payments, itch.io conducts a payment review each time they pay out the funds that have been collected on their website to a developer, so I guess it's related to that.
Pressing itch.io is futile. Their support is terrible and there were a couple of forum threads about the situation where they just reiterated their general statements, the same was true for specific support requests.