Revisiting this situation, several things are true.
1) The school was initially at fault for holding a Cinco de Mayo celebration in the first place. Cinco de Mayo is almost exclusively celebrated in the US, not Mexico, except in one state, where it is called “El Día de la Batalla de Puebla”. It is *not* Mexican Independence Day, which is celebrated on September 16.
It can properly be called “The Mexican-American equivalent of Kwanzaa”, another contrived and meaningless holiday. It exists mostly as an excuse for bars and clubs to offer pseudo-Sonoran Mexican food and drink specials to party goers.
2) This being said, the school was doubly at fault for sponsoring what is essentially an exclusionary, ethnic group event, celebrating a foreign country. This reinforces the idea that their students, even those who are legally American, are somehow still Mexican citizens, not fully Americans. It is even insulting to those children who are illegal aliens, as it suggests that they will always be Mexicans, that they will never be, can never be, Americans.
3) Only in this context of two inappropriate actions by the school does it make sense to make the third inappropriate action, by banning displays of American patriotism. But this issue is actually *not* about the white students showing their patriotism; but what about the ethnically Mexican students who want to show their American patriotism?
Even many years ago, there was a minority of ethnically Mexican students who vehemently denied they were Mexicans instead of Americans. Their families had worked very hard to become Americans, and they did not want to be dragged back to Mexico in any way. They rejected groups like La Raza and MEChA, and resented efforts to hound them into such racist and anti-American organizations. They found the notion of Aztlan to be horrific, and would have moved out of the area deeper into America instead of having to live within such a place.
So the bottom line is that those who celebrate Mexico should live there. American schools should be for Americans, and at least those who want to become Americans. And while ethnic Mexicans who are now Americans may want to enjoy their ethnic heritage from “the old country”, this should be no different than all the other immigrants are to their ancestral country. But it certainly does not mean they still hold loyalty to those places.
Indeed! And it's my birthday too.