Morbius' comment is worth reading over: you SHOULD be careful what you post on the internet, or at least be aware you are posting it in a public place.
This shouldn't mean you should feel constrained in what you do, but you should consider the implications of your words when anyone can read them for free. That being said, I have a strong distaste for limiting freedom of expression because someone is worried about what 1% of the population MIGHT think about what you have to say. Post conscientously: talk among friends with your friends; when you're in public, try and act like it.
That being said, I am quite content with that news item. It shows that the 18+ policy kept a neo-nazi asshole from buying guns off these boards. That is an unmitigated success in my opinion.