I doubt he saw them. They were 200 to 400 yards away, tracked him for twenty minutes. He was on private property.
The military were wearing ghillie suits. He may have been aware of "something", but the Texas Rangers findings were that the military lied. The angle of Hernandez wounds were such as to show that the military's version was not truthful
Also, when the Sheriff got there, the military waited fifteen minutes to tell the local Sheriff they had shot a teenager herding goats. The military did not attempt first aid, just checked his pulse while the kid bled out.
There was a huge outcry because the military could go on anyone's property, without letting people know they were there. They even were inland at times, not just along the border. Basically, ranchers here were thinking that if you were out on your property, with a varmint rifle, the military would shoot first, and ask questions later, or just kill you, and dump you in a ravine.
Thanks for the additional info. That explains it much better. His family must have been devastated.