There will always be "doubt" about that.
Fox has cheerfully broadcast lies before- their own, and other people's.
It's unlikely that they suddenly developed morals.
SoI wonder why they aren't broadcasting Trump (and co)'s lives.
I'm cynical enough to think that it's to save Trump supporters from exposure the evidence that Trump is a fraud.
If they don't see him acting like a fool, they might not realise he's a fool.
It's not going to influence his die-hard supporters or his equally die-hard opponents.
But there's a group- even now - who are undecided.
If you show that group pictures of Trump saying "the elections were rigged " but without giving any evidence,, at least some of them will realise he's lying.
And I think Fox is happy to avoid that, while also maintaining some sort of "moral high ground" by not broadcasting the lies.