Well... This is really just a base script that will be included with the bot distribution. So I want people to be able to modify it with as little hassle as possible. And as far as I'm concerned, if it filters out most stuff that resembles the word, it is doing its job.
When people start making up their own terminology (One example is "ffs" for "for f***s sake ;) ), as far as I am concerned it is an inside joke at that point. And it only really has meaning to the people who made it up. If whoever is running the bot wants to filter it, so be it. I am just making a core regexp/function that will be fairly easy to add to.

The main use I would have for it is protecting against spam advertisements. I would put in the names of other sites that people like to spam my channel with ( I mod an IRC channel for a browser game and people like to come in and spam a different game's website. If I make it so they have to sufficiently mangle the site's name, then I am happy. It isn't meant to be perfect, but it is sufficient for my needs, and as a general example script.

As far as the free speech issues, I share your views and don't really care personally one way or the other what language people use. I swear plenty myself sometimes. But as I said, it's there for other people if they want it.