No, I'm not willing to let them off the hook so easily. Why were they in a court of law in the first place? Because they lied to such an extent that it's literally illegal. If this hail-mary legal argument of "no reasonable person would believe us" was the best defence they could come up with, then that is approximately the most powerful indictment of their veracity as is possible to legally establish within our current framework. We should not let them live it down - they cannot have their cake and eat it.
At any rate, do you really think other news companies or talking heads never say things others think are untrue? The reason Fox ended up in a lawsuit is because people on the left are much more determined to take out anyone saying things they don't like than the other way around. It's not because CNN is actually more reliable.
Quoting this without understanding the philosophy of science, in context of discussion rejecting an equivalence between cable television and a peer-reviewed journal, seems like textbook whataboutism.
All published science is wrong to some degree. The point is to be less wrong, in gestalt, as time goes on. We push back the boundaries of ignorance to discover more. TV punditry echo chambers, where they revel in wrongness, are the antithesis of this process.
Example: Nature published Flaxman2020, a modelling paper by the epidemiology team at ICL which claimed lockdowns saved 3.1 million lives. People who actually read the article realized that it was a massive exercise in circular logic - the model assumed that any reductions in case numbers could only be due to government intervention. It was then presented as proof to the media that lockdowns saved lives. It had many other problems - in fact the authors themselves in the paper itself that it was illustrative only and that in reality, the effectiveness of NPIs would be lower. The circular nature of the argument was pointed out immediately but Nature only published a response letter 8 months after publication, and never retracted it.
As for your legal point, that doesn't mean much. Lawyers try any argument that might work. Facebook have argued in front of the court that their fact checking isn't actually fact checking at all, that it's in reality merely corporate political opinion, and that no reasonable person could possibly construe otherwise!