Simple: we are the adults, and we can exercise restraint, by watching shows with blue language after the kids are in bed.
Toddlers are little mimics. It's how they learn to speak, for heaven's sake. They cannot exercise restraint.
It will be all well and good until your husband asks her to follow a direction and she tells him "hell/sh*t/f**k no."
Your husband needs to be the adult in the situation. His shows can wait, I promise. We have kept the TV off in the daytime for more or less six years now, other than kid-friendly stuff. Neither my husband or I have died, I promise. Instead, this is a great time for your husband to play with his daughter.
Here's an article on basic language acquisition:
http://linguistlist.org/pubs/cupmag/pdf/O%27grady%20artic...
Here's another good article from the Pediatric Center:
http://www.thepediatriccenter.net/docs/brudenell/Understa...
Does he really need all this convincing not to be selfish in his habits?