Maybe his point isn't that cursing is bad, but that you should set an example for proper manners. Like, the language they should use when talking with schoolteachers, at work, etc.
That's my household: they'll hear plenty of salt when we play Jay-Z or Run The Jewels around the house, and it's no big deal if they cuss while telling us about their day, but we'd never tell them to "Pick up the fucking dishes."
