Big Bend, is indeed, a “on your honor” crossing — both ways, so there was some controversy re: the crossing which was re-opened a couple years ago. (Shut down with 9/11.)
But it’s literally in the middle of the Big Bend National Park -— and the Mexican equivalent on the other side. Bigger than Yellowstone, I think.
It’s literally hundreds of miles from major roads on the Mexican side and pretty much the same on the USA side. Major cliffs and impassable mountains.
You hike from the crossing to the river (in a canyon) and then cross to an old silver mining town on the Mexico side.
There are choke points on the USA point where, if you cross here) you have to go through, so even if someone crossed illegally, they ain’t going nowhere.
Literally, middle of no where — illegals will cross somewhere they can get to a town or a road, and Big Bend is not that place.
Since you know it is too remote, do you think he chose a safe place rather than a real crossing point?