Why should they care about her opinion about an American reciting another nations national anthem in an American classroom is the true extension of the question since that is the very nature of the topic/debate at hand. Her response, while you may think it is weak, is relevant and accurate. She is an American debating her opinion about an American reciting another nations national anthem in an American classroom. That is why the other person should "care", though caring or not caring si up to the individual. It would not be relevant if the person said that they didn't care but since the comment was phrased in a question... it now becomes "relevant".
I think the student did the right thing. There is absolutely no reason that students should ever be graded on reciting another country's pledge of allegiance. Having such an assignment proves that either the teacher wants the students to be loyal to another country (really doubt this, but possible) or they are very ignorant about what the meaning of a pledge is. It should not be used as a lesson for students who are citizens of other nations, and wish to remain so, to learn the language or even the culture. Recitation of the pledge does not teach anything significant about the culture.
And the school is wrong for defending this teacher as well.
BTW, another article I found said that the girl was in intermediate Spanish.
"A woman is like a teabag, you never know how strong she is until she gets in hot water." - Eleanor Roosevelt
Keep your religion out of other people's marriages.