It seems to be hosting user generated content that authors can get paid for by people that like it, so presumably it was flagged because of some content (not this particular page) that is, or at least is closer to being, pornography.

Well that's concerning... do you know if your work draws from a third-party service, and/or do you think it's possible that the "newness" of the site could be triggering that?

You should try whitelisting your site at major AV/Malware suite sites.

TREND MICRO Site Safety Center: https://global.sitesafety.trendmicro.com/

Sucuri Sitecheck: https://sitecheck.sucuri.net/

McAfee: https://trustedsource.org/

Probably a prior owner of the domain? One can easily imagine Karma as a racy name for a risqué service.

This is true more often than not, but in this case web.archive.org just shows a web radio as the previous owner.