Moderators are in a no-win situation when it comes to these matters -- if we lock threads that are racist/offensive/etc. then people get angry ... but if we don't lock those threads, people get angry. It's a daily struggle to determine what, if anything, should be deleted or locked. The only threads I've deleted are the threads of the virwex / bitcointalks spammers. It's a difficult line to walk, but I know that I - and the other moderators - do the best we can to promote and allow freedom of speech while also keeping in mind that there are instances in which leaving a thread open becomes detrimental to the community. It's a balancing act. We don't always succeed in keeping everyone happy, but we're all trying to do the right thing in these situations.