Last time I checked, a few words didn't hurt anybody. Words are just that, words. If "swearing" was such a big problem why isn't there a language filter on the server?
If you're trying to case that 'swearing' should be okay, I can tell you now, it's not something that will change. Filters can be buggy, and the plugin would have to work on every server, there's no use putting it on a few, when it could quite easily not work out on 1, but work out on another. Minecraft is a game based around a child's appeal, not an adults. As a staff member of MyM, I try my best to keep the chat PG whenever I'm online, as do other staff members, because we feel it's best to keep the server family friendly. I have a few friends on MyM, who are mothers, and who let their children play. Of course words are just words, but some certain words are not acceptable, and we're certainly not going to change our point of view, because of this statement.
There is no point in making a filter, people are already bypassing the word "lag" with l.ag l ag etc. As to allowing swearing itself, I totally agree with Ben, I could understand if you accidentaly drop in a swearword in a normal conversation, but this is a game! Before you post your comment in chat, think about what you are typing, because you still have a chance of editing out any profanity or similar from it. "Think BEFORE you act"