I'm somewhat sure that prior art requires publication, and not just knowledge. The internet archive has long been used as evidence for such publication-at-time

I'm somewhat sure that prior art requires publication, and not just knowledge. The internet archive has long been used as evidence for such publication-at-time claims, and they even have a paid service allowing you to trigger snapshots IIRC. There's a FAQ regarding the use of their data in court cases that is somewhat interesting to read. I know the cryptocurrency community has this absurd notion that nothing without cryptographic proof could or should ever be regarded as evidence. That trusting institutions, people, or processes marks you as a gullible fool, and that the Federal Reserve is conspiracy by private banks to keep the gentile from the levers of power[0]. So this is the not entirely novel situation of crypto being proposed to solve a problem that doesn't exist, and failing due to the lack of (usually: active hostility to) subject matter expertise. [0] last point unrelated to this specific situation and just included for completeness