> I don't see why a law, which generically states that recommendation algorithms operated by a publicly-owned company must bias towards intellectually stimulating content, would necessarily be a violation of the First Amendment without undermining earlier accepted laws.

This is an extremely misleading line of reasoning.

Publicly traded companies are not 'public' in the same sense as publicly owned airwaves, public (that is, government) employees, and public property. They don't cede any constitutional rights simply by offering equity for sale in the capital markets.