This is a complete troll, but a very pleasing and cleverly written one. If you search "Baader-Meinhof", you get the militant group, this article (from 2006), another article referencing the same definition without citation (from 2013), and an Urban Dictionary entry with this definition.

But the question is, by simply naming the phenomenon, even as a joke, has he created it in earnest? If you see this referenced again, then it's the behavioral psychology equivalent of the sentence "This sentence, by xianshou on Hacker News, has only been typed once in the history of creation." - a statement that remains false until it is made.