"Feels more white than Mexican" is the kicker there, I've experienced that creature in the wild but it is hardly unique to Mexicans or to any group which was ultimately folded into the social construct we call "white," which in the interest of full disclosure I definitely am. Here's the problem: she believes that as long as she takes up the cause of the powerful that she can feel like a winner by proxy, and that she may even be accepted. What you propose when uninstalling this or that racist trope she's casually accrued is that she could theoretically be part of a vulnerable minority, that she has not been born with any sort of power beyond her ken.

I don't know what to do about it either: my very Latino associate in reference went on to a photo-op with one of the Trump children and one of the smuggest "made it!" expressions I've ever seen a human make, he was finally in the presence of power. It's impossible to convince joiners that they're being duped for the membership dues.