Long before the current revision in the federal election laws, there was a provision that broadcasters MUST run any prepaid ad offered by a federal candidate (House, Senate, President). And they CANNOT censor such ads. Witness presidential candidate Barry Commoner's ad that used the word "Bullsh*t" about the Republicans and Democrats generally, and it WAS run on a national, radio network.
That network did NOT want to run that ad. But the law said they HAD to run it, and they did. The national media picked up on that ad big time and provided free ink. They never, however, quoted that word.
This has been thought through. Details like that are buttoned up in advance.
John / Billybob
For this non lawyer, although my daughter and her husband are lawyers, just wading through the syllabus of the decision was enough to make me want to go out and wash my brain. IMHO, that alone was enough to gag a maggot, as my mother would say. :)