The government should piss off and not interfere. The stations can decide whether they allow "bad" words or not, depending on who their audience is. They time of day should not make a difference. So someone sang piss, shit or fuck or some other word - why should we give a fuck?
Kids can be listening to the radio and hear cuss words and may think it is okay to cuss in public or in private. Their have been many cases where kids in a school environment say cuss words to teachers or other students who are attending the school thank you.