Free speech protection in American law is with its limits. Speech itself isn't protected if it is directed to incite or produce imminent lawless action. See Brandenburg v. Ohio.
Correct, but for that argument to hold within the context of this case (EDIT: warrant) we would need the government to show that most people who visited this site did so with the intent to incite imminent lawless action. (Note, too, that Brandenburg v. Ohio specifically struck down a law banning the mere advocacy of violence.)
Disclaimer: I am not a lawyer. This is not legal advice.
> Correct, but for that argument to hold within the
> context of this case we would need the government to
> show that most people who visited this site did so with
> the intent to incite imminent lawless action.
If this warrant were replaced with demands for visitation logs from specific IP addresses or relating to certain people, it would be far less controversial.
Also, at the heart of banning bad speech is the fear that your fellow countrymen are too weak and stupid to deal with political, racial, sexual, or just scientific thought in general, and you fear the democratic reigns in their hands.