They have power because they have unlimited free money. They or the DOJ can sue you for libel and damages. Your speech won't be illegal but it most certainly will harm their authoritarian efforts in some way, costing them (the taxpayers) money. Maybe they need to add a security guard. Maybe they need extra policing online now. Whatever, those are your damages same as if you ran over a fire hydrant. They'll convince a judge and you'll be financially ruined. That's sufficient to shut most people up.