It may not have been fleeting by the dictionary definition of the word, but it definitely was by the way the rules are applied. I've worked in the broadcast industry and have had to deal directly with this subject, so I'm not just spouting nonsense here.
I've also worked in the broadcast industry; you are just spouting nonsense. You get fined for knowingly allowing several minute long continuous chants like that, and can get your license taken away.
It wasn't fleeting in either the dictionary nor the regulatory sense.
Oh yeah, the FCC would have smacked them but since the reporter "pretended to mishear the crowd" their plans were foiled!
Do you have any idea how ridiculous that sounds? The reporter has literally zero control over what gets aired aside from the words coming out of her mouth. What she "pretended" to hear couldn't be less relevant.
The reporter knows that a long chant repeating the word fuck makes an interview unairable unless they have some semblance of cover. It's literally their job to produce raw footage that can be aired. 'Not hearing' the profanity has absolutely worked before for getting out of fines. The FCC is a giant bureaucracy and can be sort of hacked that way if there's regulatory 'case law' like there exists for this situation.
I agree it's not full proof, which is why I think the production staff if anything went out of their way to broadcast "fuck joe biden", contrary to the discourse on the matter.
The production staff almost certainly went out of their way to include it in fact.