Are you telling me that he actually issued demand letters?
It looks like an attempt to scare a few people off. He's probably hoping that at least one or two of the recipients will take down their content. If anyone actually posts an apology, it would be a pretty big win for him. And if anyone sends any money in response to the letter, he gets to pocket some easy cash at a detractor's expense.
If he can get at least one or two people to fold without anything more than a badly-written "letter of warning," he can use that to attack the others and build up his claims of, well... I'm not sure he's out to prove he's innocent at this point, he'd just like to strike back at anyone who isn't supporting him.
The proper response, IMO, would be for anyone who receives the letter to find a local lawyer who will provide a free legal consultation (this letter shouldn't take long to address) and then make a video mocking Evans for such a blatantly desperate grift.