The U.S. Constitution applied to him then, just as it applied to him later when he was sent to a U.S. prison for a subsequent crime in the United States.
No shit Sherlock. So pick a post that actually applies as an example. According to you they abound. The reason Davila was shot at was not that he was a drug dealer or smuggler nor that he was a Mexican (nobody saw his passport). He was shot at because of his actions.