A verdict that shows so: http://www.asesoriayempresas.es/jurisprudencia/JURIDICO/1959...
Taking the article's example, would you be liable for ranting about a drunk driving checkpoint being a shakedown?
Which translates: "Effective knowledge by the plaintiff of the stored messages by third-parties on his website. Fax receiving in which [the admin] was informed of the lascivious messages to the plaintiff. By refusing the FAX the defendant breaches his duty of diligence"
So this case was about sexual comments against a specific person for which the owner of the site refused to delete such comments; so little to nothing to do with censoring messages against the state.
For the smaller casual "circle of acquaintances (relatives, friends, coworkers, gaming teammates, etc)" chats, there should be no owner, though - small non-public invite-only communities work perfectly well without administration. This doesn't solve "poster is responsible" but it solves "owner is responsible".
For larger or open chats - yes, the owner should be someone pseudonymous (or just a robot).