I think it's fine to build NLP models with any desired property you like, including "not leaking vulgar opinions that offend the courtly manners of your society." Makes plenty of sense.

But I do wish people would be more frank and self-aware about these purposes, rather than fig-leafing it as "ethics" or "fairness". By the time you've deliberately omitting the US Congressional Record on grounds of problematicity, it's worth asking yourself whether you're making your bot polite or doing damnatio memoriae.