"It" did actually happen, shortly after the post, and was therefore both imminent and likely.
This was also the second such incident within just a few weeks. Knowledge about Christchurch should maybe have informed these "shitposters'". Can't really claim it's all just a joke after people have died.
The jokesterism is in response to a joke world. There are innumerable numbers of murders each year but somehow a spree killing is enough to slay irony? 9/11 wasn't enough to slay irony. The reaction to it excaberbated the ironic mode of moderm culture.
This was also the second such incident within just a few weeks. Knowledge about Christchurch should maybe have informed these "shitposters'". Can't really claim it's all just a joke after people have died.