I haven't been able to find any recourse. The malware was online for a few hours but it has been weeks and there seems to be no way to clear my name. Someone on github (the website is open source) suggested that it's probably because they didn't know of the website, like everyone heard of wetransfer and github and so they don't get the whole domain blocked for malicious user content. I can't find any other difference, but also no responsible party to ask. The false-positive reporting tool on quad9's website just reloads the page and doesn't do anything
¹ I'm aware DNS can't do this, but with a direct way of contacting a very responsive admin (no captchas or annoying forms, just email), I'd not expect scanners to resort to blocking the domain outright to begin with, at least not after they heard back the first time and the problematic content has been cleared swiftly