They used the term LARP a lot more literally than I expected.

  Although the history of LARP as a legal defense is narrow, the authors share the concern that it may soon become commonplace. Early attempts at such a strategy have been made by a defendant acting alone or in loose cooperation with members of a fantasy group who knew each other only in the virtual world, claiming “artistic expression” to excuse threatening language.

I can see this being a big problem with memes in the immediate future. Does the FBI have a page where they attempt to distinguish edgy memes from genuine calls to violence? This is a relatively benign example, but there are TikToks where users pretend to have fantasies about taking officer's service weapon. Sure they're all jokes, but modern internet humor is deeply ironic; I'd imagine there are plenty of genuinely violent people making seemingly ironic memes. I'd also imagine that there are nonviolent memers disseminating genuine violent ideas and vice versa.