People seem to take enormous psychic satisfaction in defending Brian Dalton's creepy journal. Oh sure, we get the dutiful statements of personal revulsion at Dalton's fantasies. But, oddly, the more repellent his writings are, the more they give Dalton's defenders the self-satisfying sensation of rising above the angry mob calling for his head.
It doesn't matter that there is no angry mob, since everyone is with Dalton. Still, there could be an angry mob.
Defending counterintuitive positions makes people feel like abstract intellectuals, capable of grasping the larger point beyond the ken of the little people. But just because something is counterintuitive doesn't make it true. (College students everywhere, just beginning to practice this annoying pretension, are staring blankly at that last sentence.)
Acceding to the nonexistent pressure from hoi polloi and punishing Dalton for his journal, the argument goes, would be the first step on a slippery slope to fascist thought police banning all controversial opinion.
Slippery slope arguments are always stupid. Please stop making them. What people think they mean by "slippery slope" is that the principle at the top of the slope is indistinguishable from the principle at the bottom of the slope. That's a bad principle argument, not a "slippery slope" argument.
For a slippery slope argument to work, what is at the bottom of the slope must be more horrifying than what is at the top of the slope. Obviously, therefore, there's a difference between the top and the bottom. If you can see a difference, so can the law. That's how we end up with exceptions to general rules.
At this very moment, for example, you are prohibited from engaging in speech that: expropriates the official NBC logo, reveals Coca-Cola's secret formula, defames a private person, would likely incite violence, unduly exploits someone else's work, is a false boast about a product, gives investment advice without registering with the SEC, is too loud, or rebroadcasts Hugo Zacchini's entire human cannonball act (see Zacchini v. Scripps-Howard Broadcasting Co.).