I think GP may have worded it a bit strongly. What seems to often happen is that when there are many people from the same original culture living together whatever cultural pressures there may have been in the original country will tend to reproduce. This is probably related to those people being marginalised in the host country, so they don't have a lot of close contact with the new culture. Their day to day interactions are with people sharing the same views.

This seems to happen less when people are living among different cultures, even if those are all "foreigners" in the country.

I can see this phenomenon happen also with "expats", particularly Americans as its pretty easy for them to find each other. I've met many such expats around Paris who had lived here for several years and could hardly say a word of French. But I guess that the "culture shock" isn't as strong because US and French cultures aren't as different as say French and Indian.