Supplements are regulated in the US as foods, not drugs. If the makers of these supplements claim they treat, cure or diagnose any disease the claims can be censored.
>we shouldn't engage in censorship of factual information
Most of what was said about fake covid cures was not factual and/or exaggerated. The case could certainly be made that many of those promoting said solutions stood to benefit commercially and politically from spreading the false information (including many senior politicians).