Corrupt Mexican government officials need El Norte outlet to prevent civil unrest and war within their own country. They will push, finagale, and outright defy US convetions to secure the border, eventually up to the point of war with the US, IMO.
They do not hesitate lying about the incident.
"Authorities said Martinez was on the Mexican side of the border at the time, but may have picked up rocks and made motions as if to throw them at the U.S. agent."
USBP's report is very different.