The FCC exists (in part) to enforce a certain morality on public broadcasters. Whatever we think about that today, that was a core responsibility of the FCC when it started and that still exists today.
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A list of words you can't say is about morality; it's a drag but at least it's objective. You either said the word or you didn't.
This is far more subjective.
In fairness to the provision, I think it's outdated, and I've argued against its relevance and that it seems unlikely to me to stand up in any court that interprets 1A jurisprudence to a modern standard, but the law exists and exists specifically to prevent against broadcast lies.