I wonder too. If this were some kind of home-room ritual outside of Spanish class-- then some massive measure of outrage would be warranted. But I too remember learning "La Marseillaise" in the two years of French class I took. (Slight correction to your French, there...) The reason for the focus on Mexico rather than Spain is obvious, given the proximity of Mexico. I think most high school Spanish classes focus on Mexican rather than Castillian spanish, for the logical reason that it is more likely to be useful. I share all of the outrage at the horrible border enforcement and illegal problem. I cringe and start loading weapons when I hear the word "Reconquista"... But folks, seriously... This is a ~spanish~ class. It's not Miss Marple's morning geometry home-room class.
Sorry about the gender mistake, it’s been a long time since I wrote anything in french.