They are not stopping the programme but merely pointing out that the language used is from another time and has now been recognised as possibly liable to cause offence.
I think it's just common courtesy.
Or do you think it's OK to for words like slag, cretin, pouffter, retard, gyppo, chinky, etc, etc, etc, to be used in the context of a comedy without comment?
Genty Whether a French person living in, or visiting, this country in those days considered French people being referred to as frogs as simply "harmless fun" is questionable. Words are often considered to be harmless until their use has a personal impact.