Except when you find out the author/editor/reviewer of the text has a name like "Ayad Al-Qazzaz." And that other parts of the text are filled with anti-Israeli tripe. Then you realize that it's not silly but a quite serious attempt at Muslim indoctrination of our schools.
The only reason a 21st century textbook would call Jesus a Palestinian, and not a Jew, is for purposes of indoctrination. Do you have German background? If so, it would technically be correct to call you a Hun, but any reasonable person would wonder why I did it -- humor or insult, but not without motive. Same as if I called an Asian a Mongol, or a Russian a Cossack.
As my Dad used to tell me, when something doesn't make sense, look to motive.
Suggest you read the source article.