We already got past that with search engine's auto suggestions for instance. If you Google "Australia is" you'll get a list of suggestions that could be construed as coming from Google, but most people understand it's just from statistics, and those still making a fuss about usually get ignored (political corruption aside).

Sure your client could want to be ultra sure, but I'd argue the censorship coming from a marketing concern doesn't make it specifically better. If I actually use swear words all the time for instance your software would be constantly penalizing me.

That's a tradeoff they're willing to make, but if I was a user it would be totally fair for me to be pissed and hold it against them.