The Nazi banner is outlawed in many European nations. Facebook is a website with an international customer base so the person who initiated the page probably wanted as wide as an audience as possible.
Factually, Singapore, which is mentioned on the Facebook page, did not become a city-state until well after the war. It was part of the Malayan colony.
True about Singapore (and the flag used), but it was certainly an island/Crown Colony/city before and during the war.