Had cops show up at the home of a child that was on a sports team of my daughter's. They were looking for her brother and took him in.

Afterwards we spoke more to her mother and found out that users in game forums had told him he could make these kinds of comments and it was free speech as long it wasn't a call to violence. Well I don't know the legalities, but I do know he was never welcome back at that school. (Nor even in the district for that matter.) Worse, the neighboring district got word, and they implemented their own machinations to ensure he was effectively banned from there as well. In the end, they sent him to live with relatives.

I wouldn't be so cavalier about telling people they can say things like this. It's like, well you can say anything. But if you say things that make oblique suggestions towards violence, expect to watched from that point on. And excluded from any activities that people believe would provide you opportunity to act on what they now suspect to be your intentions. You can't talk about indirect suggestions of violence against airliners, presidents, or students in high schools and still expect to be able to show up at the White House, or board an airliner, or go to the high school you attend. Society doesn't work like that these days.