-- And they don't all agree on what "adult content" is. --
And there you got a very good point. Since "adult content" is also a bit subjective.
And let's also be wary of false positives, as some words may imply "adult content" while in fact it's not. I've been banned on Twitter for 14 some years ago by a bot-moderator for using the word "trigger", as that was a death threat. (I was using that word in a completely different context, though).
Indeed, as soon as I see software packages of which the developers claim the impossible, I personally walk away as fast as I can.