It is not only unrealistic, but also an outdated 19th century view of geopolitics, with a history full of racism, genocide and other horrors.
That's literally the opposite of colonialism.
(by "weak" I just mean the opposite of prolific.. not sure what the right word would be there, i.e. Judaism has super strong ties to Israel- agricultural laws of orlah and shemittah, recorded purchase and significance of Hebron, daily prayer for over 2000 years to rebuild Jerusalem. No other religion has anywhere near this strong of a connection to the land).
The colony in Palestine took off, due to the British preference of solidifying european control over Ottoman region, and the convenient façade of the historical claim.
People lived there before this are descendents of those who lived there in the past. Many stayed even after the expulsion by Romans, many returned. Some, obviously would have changed their faith, but none of that gives the European descendents any more right over it. We can all colonise Ethiopia if we were to go on like this.
I am not interested in debating Ethiopia, I know nothing about it, and wouldn't presume to take a strong position on a subject I know so little about.
"Usurpers" in that context was specifically about religious claim, where Islam has both a far weaker and far later claim than Judaism
And then a few more, for good measure.
The only legitimate heirs to the region are the Bronze Age Canaanites. The only legitimate religious claim is held by the followers of El and Asherah.
All others are usurpers and latecomers.