This is the real answer.
CBS not fact checking gives the liar a strong advantage.
The moderators not fact checking is fine for things like debate competitions because the judges are experts.
But in a public debate, an opponent even responding to a lie legitimizes the lie. “Of course he’d say that.”
When a candidate lies and the facts are readily available to the moderators, it is imperative for the public good that they fact check.
Honestly, it is such an obvious lie, too. Can companies really just lie in their filings to the FTC?