free speech doesn't apply to private property. and this is private property.
My friend, its your site and you can make the rules like you choose, but I suspect you are gonna have a hard time enforcing those rules especially with big numbers of very diverse people, with very diverse ideas, frequenting the site.
"What's wrong with being a Catholic?"
I understood him to mean by "forbidden term" the reference to religion, the forbidden topic, and not a slur against the Cathloic Church, which he seemed to hold up simply as a benchmark of conservatism.
Thanks batgirl, that were my exact intentions.