This is misleading. It seems like you're predicating your entire argument on the idea that there is a version of Section 230 that would require platforms to act on user reports of discrimination. But you're fundamentally misunderstanding the law's purpose: to protect platforms from liability for user content while preserving their right to moderate that content as they choose.
Section 230 immunity doesn't depend on "actual knowledge." The law specifically provides immunity regardless of whether a platform has knowledge of illegal content. Providers can't be treated as publishers of third-party content, period.
It's not that "'actual knowledge' no longer matters," it's that it never mattered. Anti-discrimination law is usually for things like public accommodations, not online forums.