Look. Mexico is a sovereign country. When you are in their country, you are subject to their laws, good and bad. Whether it was by accident, stupidity, being drunk, or what ever, he took a loaded arsenal, by any bodies standards, into a country where it is illegal.
Good grief, what would our police do if they caught a Mexican Citizen coming across our border with such an array of weapons, loaded and ready to go.
Let it play out in their courts.
And by the way. I am a combat veteran. I got all blowed to shit and back in Vietnam. That, and $1.50 will get me a cup of coffee at Mickey D's. so get off all that Marine crap.