Cable channels can broadcast whatever they want. Ever hear some of the language on FX original series shows?
Ok lets split hairs then.
A show that gets aired on a movie/drama channel has to have a disclaimer before a show with vulgar language. You're wrong. Not ALL cable channels can broadcast what they want.
The discovery channel broadcasting vulgar language? I think not. A movie/drama channel doing that with a disclaimer beforehand? Perfectly fine.
Its not 'absurd' as you put it. Its perfectly reasonable that a family-friendly channel doesn't broadcast words used in a vulgar manner.
/off-topic