First of all, as I understand it, the person bringing a suit has to prove real and actual damages to him, whether to his reputation or economically. There are literally hundreds of thousands, if not millions, of comments being made on the internet about this case; it would have to be proved that any of our comments are not only false, but that we intended to damage him and that he was harmed financially (or socially). And it would have to meet the level of what a reasonable person would believe as fact. If you called DP "Satan", for instance, no reasonable person would believe he was, in fact, Lucifer.
Mr. Peterson has more problems with the damage he's done to his own reputation, IMO.