The free speech crowd are entirely missing the idea that this is a civil suit. No element of government is attempting to enjoin Jones from speaking. The families of children killed at Sandy Hook claim Jones defamed them and seek damages to redress the harm he did to them.

This is ordinary U.S. civil law. Yes, you can speak freely, and the government cannot stop you from speaking. But if that speech is false and defamatory to the point that it hurts people, they might sue you for it and win.