I'm surprised a well informed (LOL!) guy like you wasn't aware of Mexico's paranoia about foreign exploitation of their oil. Mexico will never enter a union with the US because they're afraid we'll steal their oil. Get it?
Yawn. That’s like worrying about Hugh Heffner stealing my 80’year old granny. The Mexican reserves were never as grand as she was in her prime and they will probably be dry before she passes on.
Besides, if we did want that low grade sulfur ridden crud... well, I understand folks are doing amazing things with slant drilling technology these days.