Something doesn’t seem right to me.
He has ‘de’ in his surname, which is French for ‘of’ or ‘from’, but he is from a german speaking part of Switzerland.
Graübunden, and Switzerland, at the start of the 20th C was very poor and many emigrated to seek a better life (my ancestors included).
He turns up in a remote part of Australia claiming to be related to all sorts of notables.
Hmmnn!
The item Jorose linked is intriguing but I cannot work out the context of it.
However now we have more vital facts there’s much to build on.