There are so many open source games that people could upload to itch.io, and I would love to be able to play Sauerbraten or Hedgewars from the itch app.
I also understand why you would not want to allow random people to upload their own HedgeWars builds.
But if open source uploader just "forked" Xonotic and called it "Shmonitic", that would be totally within the rules, right? Or any re-branded "fork" for that matter? Not that I'm advocating for asset flips! I just want to make sure I understand your concern. I think your concern is either people piggybacking on the success of certain games to distribute adware, misrepresenting themselves as the official developers, or a flood of near-identical uploads because I have as much right as the next guy to upload Xonotic to itch.io, as long as I honor the GPL.
But if I call my game "Shmonotic", then I won't mislead people who google for the official "Xonotic".