I don't agree with the sentiment, but I do like the disruption. 

Is there not a legitimate capacity to limit free speech in the school (or camp-out setting or at the range) when dealing with young people?

The enforcement of "dress codes" are more or less individuated from provocate statements aimed at specific elements of the community. But it's essentially the same issue.

And for the record, rights do not exist for children in my house as such. They don't have rights, they have protection. It's really a benign dictatorship.