Jessie, I understand the point you're making in an historical, social and ethnic sense.
None of that changes the fact that if you add an 's' to palestinian (when intending it as an adjective) it's not correct. eg you can't say "they lived a palestinians lifestyle": if you wanted to suggest they lived a lifestyle of a (so called) Palestinian person, then you'd have to insert an apostrophe before the 's': "...a palestinian's lifestyle".
Not worth arguing further about. It was probably just a typo in the first place.
