While it was certainly very wrong for those people to walk out, I can understand the feeling of those who believe that in the United States sermons should be in English unless the parish is specifically spanish speaking. It is a big deal for the English speaking members of the congregation to have to listen to a sermon in a foreign tongue once a month. It does feel like displacement.
I disagree with you
Telesphorus. Prior to the Second Vatican Council, the Catholic Church in the United States catered to different Catholics of many ethnic backgrounds by having the priests do the sermons in their native langue as well as Catholic hymns.
My Polish Catholic teacher who grew up with the traditional Latin Mass related to me that her parish gave Sunday sermons in Polish and English. Catholic hymns in her parish were sung in either Polish or English. She even stated this applied to the Czechs, Lithuanians, Italians and their respective dialects, Hungarian, German, etc. These European-American Catholics preserved their culture within their Catholic parish while remaining in their mother tongue, English.
When I was in the Novus Ordo, we had a Spanish, Chinese, and English sermons. Making our parish "multicultural" also increased the Catholic devotions that American Catholics seem alien to. We had Catholic fiestas, especially for the Santo Nino (Holy Child). In fact, we had Anglo-Americans who became devoted to the Infant Jesus of Prague as a result of sharing our Spanish Catholic culture to them.
We had no problem with the diversity because lots of the immigrants belonging to the older generations have difficulty comprehending "big words" in English. Imagine saying, "sanctification" or "propitiation" to an elderly Chinese Catholic who only knows basic communicative English skills.
During the pontificate of Pius XII, Cardinal James Francis McIntyre (the Metropolitan of Los Angeles & close friend of Cardinal Francis Spellman) had to increase the usage of Spanish sermons for the Filipino Catholic community because of their population increase within the Los Angeles archdiocese.
Here in the Philippines, we have American and Canadian priests giving sermons in English in the traditional Mass and they don't have any intention of learning how to speak Tagalog in my family's country which I find absurd. In the Novus Ordo, the foreign Western priests speak Tagalog in order to teach the Catholic Faith to their congregation and they adapt to the locals' culture.