And if these Latino students are here legally why would they be offended by a reference to protecting the border?
Because Latino extremists think that the southwestern United States belongs to Mexico, it is all theirs, and building a wall is an assault on their freedoms.
And too many of them associate with Mexico over the US in terms of pride, so American pride is offensive to them. That’s how you got kids suspended for wearing US flag T-shirts on Cinco de Mayo in American schools, as incitement of violence.