I am going under the assumption that his ancestors came to America, and that he is an American. It may not be his responsibility to encourage immigrant Hispanics to speak English, but it would be to everyone's advantage.
No one is saying that legal immigrants are unwelcome, but that when they do come to America, at least be part of America and speak the language.
Those of us who are also descendants of immigrants, or Native Americans, certainly understand. The sooner they become full-participation citizens, including speaking English, the sooner they will succeed. This is for their own benefit, not for those who don't want to hear their language. Drop the labels and become Americans!
That's why we're called the United States of America.
And not the Separate States of Foreign-Speaking Immigrants.