As far as free speech goes please see Supreme Court cases Brandenburg v. Ohio, and Schenck v. United States, basically outlines why you can't yell "Fire!" in a crowded theater. As far as the kid goes, 7 years is pretty harsh. Community service without a doubt (washing out the rear end of garbage trucks or something), and maybe parade him around from school to school as an example of what can happen if you think malicious speech is funny.