You never gave up your right to freedom of speech. However, you did agree to follow the form rules (Located in the Rules Of Conduct & New User Guide) when you signed up on the board. This includes not being able to discuss anything relating to the topics you mentioned above. If you didn't agree to them, you shouldn't have signed up to use the forum.
Just wondering, how can mods lock threads that are an honest post about something that is "against the rules" (ethnically, racially, religiously or sexually offensive, insulting or demeaning)? Now I'm not really talking about the insulting/demeaning part because it is hard to be honest about an insult or a sexual comment, but what about ethics, race, and religion? You could make an honest post regarding a question about those three, but where did we give up our First Amendment right? All I'm really lookin for here is a good answer.