He landed in Australian territory in September 1939. The war had just started on the 1st of that month. Even if he had met someone during those days/weeks, chances are they hadn't heard of Hitler's invasion of Poland either, or were simply not concerned about it.
I remember reading that prior to Indonesia's declaration of independence in Mid-August 1945, in Jakarta (the capital of the Japanese-occupied country), there were rumours that something happened in Japan... 2 atomic bombs, and only rumours!
Also his route linked above shows he actually went all along the northern and eastern coast of New Guinea before arriving in Australia, at that time news was probably hard to get in that part of the world!