The Mismeasure of man was written by a Jew, and helped to subvert Western society by promoting the idea that there is nothing unique about Europeans that makes them more compatible with Western Civilization(which afterall is a product of European people). Therefore you can replace Europeans with anyone and get the same results.

I suspect those Jews you encountered that seem to sincerely believe the bullshit are fully aware of this, or at the very least have never looked at it critically because it seems to perfectly align with and advance their agenda. Were the same book be used to promote mass immigration to Israel, Jews there would be highly critical of it, including ones that previously appeared to sincerely believe it.

Many Jews in the west like to play good cop, and leave playing bad cop to those in Israel, who can do so without facing criticism because of a Jew centric media and the persecution complex and double standard that justifies behavior in them that is seen as evil in non Jews.

If the subject of Israeli's extremely unwoke behavior comes up in the US, most liberal Jews in the US simply shrug and say yeah that's bad(and sometimes say im not Israeli so whats it got to do with me?), knowing nothing will be DONE about it, while in the US being "bad" in the same way will get one cancelled or worse. Others of course will simply accuse you of antisemitism for even mentioning it.