1) Fear of outsiders is not ‘a thing’ but a universal human reaction. Or at least it is outside of northern europeans. It is not an irrational fear. It is a rational fear. That is why humans bear the intuition. It is an instance of the disgust response.
2) The Fear of Catholics and Jews was warranted. Any student of intellectual and legal history will have trouble arguing otherwise. Prohibition was an example of the reaction to catholic immigration. Jews have had an equally negative effect in a number of areas. YOu can say in both cases that we have endured those negatives. But it is very hard to say that between the catholics and jews that rule of law persists. (you may not like it, but it is what it is.)
3) High trust society resists lower trust cultures. And we pay the price for integrating lower trust cultures with traditional families into high trust culture with absolute nuclear families. It is what it is. Trust decreases, civic participation decreases, economic velocity decreases. (and yes that’s the case, although it’s very contentious, I am pretty sure I can hold that argument against any economist living).
So it is a rational instinct (we evolved it for a reason) and a rational fear (empirically the consequences have been catastrophic since 1963). And we require both empirical and operational means of testing such statements to the contrary.
(Human perception being one of frog-boiling intertemporal incompetence.)