Christ. Not the old "first they came for the dogfighters and the chick-squishers, and I was not a dogfighter or chick-squisher" cliché. Look, first of all, Nazis are allowed to march and racists are allowed to spew as long as no one gets hurt. It's not that complicated.
These idiots keep looking around for a line to draw, and it's right fucking there. Dogfighting is illegal, animal abuse is illegal. This is not a "free speech" issue, it's a "causing harm to others in clear violation of the law" issue. The laws are pretty clear about those things, just as they are about kiddie porn. No court is going to confuse a PETA jeremiad with a crush video. Obscenity guidelines typically revolve around prohibiting content that is overtly salacious or prurient. And as obnoxious as PETA's exhibitionism can be, there's a huge and obvious gap between their tactics and those of these twisted assholes.
(And seriously, the bastards who get their jollies from watching the unwilling and helpless be raped and abused, tortured and killed, they need to have their fevered brains splattered across the nearest wall, right along with the actual perpetrators. Just be done with it. Trust me, no one will ever miss them.)
I'm not sure what the self-styled First Amendment absolutists see in tilting at this particular windmill, that our civic lives and freedoms will be unnecessarily circumscribed by preventing these vile people from doing these vile things. Sometimes the theorists need to get out of their ivory towers and take a stretch in the real world, and think about the unnecessary damage that gets committed under their rhetorical umbrellas. I'm betting most of them were upset about Michael Vick, and Robert Stevens and these crush creeps should be no different.