It still remains a fact that no country claims that territory. And that's interesting in some abstract way to people with the fantasy of forming a country. Which is exactly what the parent comment was referring to.
The whole thing is just meant in fun. Aside from the fact that the treaty binds only the signatories.
The café was opened in 1876, and in the late 19th century it became a key meeting place of the Viennese intellectual scene. Key regulars included: Peter Altenberg, Theodor Herzl, Alfred Adler,[2] Egon Friedell, Hugo von Hofmannsthal, Anton Kuh, Adolf Loos, Leo Perutz, Robert Musil, Stefan Zweig, Alfred Polgar, Adolf Hitler, and Leon Trotsky. In January 1913 alone, Josip Broz Tito, Sigmund Freud, and Trotsky (the latter being regular) were patrons of the establishment.