Because Iraq is a Muslim country and such behavior is more commonplace with Muslim immigrants who are not interested in integrating to a country they chose to migrate to.
Chances are this Iraqi immigrant wasn't a Chaldean/Assyrian because Iraqi Christians don't engage in this behavior like the Muslim Iraqis often do.
Sorry if that may seem 'bigoted' to you, but I suppose the truth hurts.
Coming from someone that hates non-Muslims, you should be the last to talk.
So it is your stereotype thinking which led you to conclude that because he is from iraq and Iraq is a Muslim country therefore Muslims are to be blamed. What brilliant thinking. regardless fo the fact that he himself blamed it on Iraqi culture you are not prepared to believe him. What does he know, you know better. Whatever the truth, haters who sterotype and try and blame whole communities and religions to satisfy their hatred are to be pittied.