One cannot be sure, but the part of the article that probably upset her the most was when President Fox is quoted:
"To be so repressive isn't democratic or free ... to be putting up fences, chasing Mexicans, that isn't right," Fox said. "The U.S. needs better answers than repression, weapons and violence."
That counters all of her favorite talking points, and would leave her nothing to say. No wonder she is so angry with him.
SIDENOTE: In the comment threads, a McBride fan (and/or possible student) carries on in the proud McBride tradition of making wild accusations that are nowhere near being based in fact, nor to be found in the article.