I suspect that the argument against multiculturalism here is that it does not feed Euro-American white evangelical Protestant elitism.
You suspect incorrectly. The argument against multiculturalism has nothing to do with the culture of any particular country. Someone could get into a taxi cab in any country, and if the driver does not speak that country's language (or speak it intelligibly), they've got a problem. This is just one example. Generally, nations have a culture. And when people come along who are of a different culture and do things differently, that causes difficulty for everyone involved.
This is why nations are nations, instead of whole continents of just one nation, Because there are cultural groups, who (primarily by language) can only coexist with one another.
Ever notice how the names of nations are the same as their language ? (England-English, Sweden-Swedish, Germany-German, Italy-Italian, Japan- Japanese, China-Chinese, etc
NATION - a stable, historically developed community of people, with a territory, economic life,
distinctive culture and language in common (Webster's New World College Dictionary, 4th ed.)