You do have to admire the Border Patrol agent’s restraint in this case.
I’m sure in their hearts they would like to do what you suggest. But, if they do, there’s the paperwork, and the investigations, and the hearings, and the lawsuits, and the (fill-in the blank) ad nauseum. All that is bad enough even when you don’t shot them. It’s worse if you do. And really worse if you kill one of them.
Better to subdue/taser the SOB if you can and run him through the courts for attempted murder, give the worthy a nice long prison sentence then deport him as an old man back to wherever.
We need a vigilante black ops force working the area down there.
I reckon that’s all true .. for now.