So the Jews living in Palestine and elsewhere were somehow supposed to magically tell the difference and not obey the terms of a treaty their sovereign had signed?
I don't see how it is irrelevant. Check the timeline.
Remember, this is post-WWI, when Empires were broken up into nation-states. If your majoritarian principle had been accepted All Europe between the Rhine and the Ne'eman would have been remained part of one Germany instead of being divvied up into Germany, Poland, Austria, Hungary, etc. The rule was "no more empires" (other than those of the victors, of course) and that fate was applied to the Middle East as well. Since the Arabs of Palestine didn't consist of a nationality of their own, they didn't have to have their own state. They could remain as a minority in a Jewish state instead, just as some Hungarians remained as minorities in Romania.