That's the theory that most of the western worlds population takes, I think, that you have to put up with the detrimental proponents of change else you risk silencing the beneficial ones (And yes, I know both those words are open to debate depending on personal definition). However, spreading an idea as something separate from personality is hard, it has to be a really good idea. Most religions have 'central' human characters, whether desired by those people or not, the 'cult of personality' is a meme that works.
Now, I'm not saying it should be difficult to get his name if you so desire to know it, my concern is with the saturation of Media with Breivik as a person that stands a risk of raising him to a similar level.
With regards to 'underground beliefs', I think we need to remember we are still human to a certain degree, I don't care if a guy is dating a rubber blow-up doll for example, I think it's a bit wierd, but as long as he's not expecting me to do the same, fine. I do care if someone thinks Slavery should be re-instated however, the difference is that I would actively seek to stop that, whereas I wouldn't consider someone who shagged a rubber doll to be a danger to the world around me.
Society should take care of itself, no-one else is going to do it, the problem is, the guy who got caught shagging a donkey is far more likely to be ostracized than the man claiming that all Gays should be burned at the stake, in fact, he could be local priest. That, for me, is where it all gets a bit silly.