Frankly, the Spanish version was no more offensive to me than Jimmi Hendrix parody on the Vietnam War and the National Anthem or almost any World Series, Super Bowl rendition in the last 20 years.
Nonetheless: One of the early assignments in Miss Mary Belle Warren's (Parlez vous Francais,y'all?) French class, Fairmont High School, 1959, was to learn how to sing "La Marseilles" (pardonnez moi, j' ne souvenir pas le ortographe "La Marseilles" correct), en Francais. Mary Belle's point (pointe?) being that we learn the things that make up the French culture as we learn the language.
I can't imagine the French, given their extremely protective sense of their language, culture and history, would deem it appropriate to have the Algerian Boys Choir sing their song in Arabic.
Wouldn't it seem natural then that one of the first things you would learn in English for people who want to be American's is how to sing the National Anthem in our language... and I don't give a damn if it isn't an "official language" by law, it is the accepted language of all of our important documents and correspondence from the Mayflower Compact, to the Declaration of Independence, The Constitution, The Gettysberg Address, our money and the last State of the Union address (though Dubya does not necessarily speak anything that most of us would recognize as English).
The Anthem, in English, is a central part of our American culture. If you want to be a part of that culture you learn to sing the National Anthem in English.
I note the use of "Nuertos Antiem" as the song title, NOT "Antiem Nacional" (excuse please my slaughtering of the Spanish) "Nuertos" I'm assuming to mean "Our" or Our Anthem, not the National Anthem.
What seems to be emerging as I watch this issue play out is that there is a separatist movement afoot, one that intends to supplant a dominant Anglo culture, with a Latino culture, that for many, this is a part of a long range goal of re-taking the continent.
BTW, I recently began taking German, but I don't think we're going to learn how to sing, Deutschland Uber Alles, for PC reasons.