Just to provide you with some information about the reins and a few other things...
Most western horseman, especially those who ride “working” horses, ride with “split” reins that are not one continous loop and the reins are NOT tied together in a knot. The reins are connected to the bit via a water loop, which is a separate piece of leather. A leather “fuse”, similar to a shoe lace, is used to connect the water loop to the rein.
Heavy Oiled 3/4" X 8' Water Loop Reins
The reins are used this way for a reason. If something goes wrong, like a horse getting tangled in a rein or pulling back, the fuse will break instead of the expensive leather rein. Most sets of reins I own cost over $100 per pair, yet a fuse is less than $1. I carry spare fuses in my saddle bag and trailer.
It may have been thought that someone else had dropped Ben and his horse off elsewhere because it was initially reported that his truck and trailer were in his driveway at home. Depending on the size of the ranch, terrain, weather, etc. it is sometimes easy to haul into more remote locations, and then ride out from where you leave your rig. It sounds like Ben rode out from home, as no one has stepped up to say they dropped he and the horse elsewhere.
Another thing to keep in mind is that horses are prey animals, which means they have two options for survival, either fight or flight. Most horses would rather flee than fight. I am sure Ben’s horse is a typical ranch horse- well broke, steady, fit and strong. Think of the horse as the cowboy’s means to do his job, like an IT person relies on a computer monitor and keyboard. Ranch horses spend uncountable hours under saddle- hours of daily riding, standing around waiting for things to happen, standing tied to a fence, trailer, etc. BUT, horses are living, breathing animals with minds of their own. They can become spooked or frightened, slip and fall, or experience behavior issues caused by things like pain. And all of these things can cause them to unseat a rider without much effort.
I own some REALLY good horses. Well behaved, broke horses that have been hauled all over creation. BUT, they are still horses that can react given the situation they are in. Depending on what spooked them, I would never count on a horse to stay with it’s rider if they became separated. Horses and dogs are not similar in that aspect.
It is easier to come off a horse than most people think. One the best upper level riders in our country, Olympic level rider, came off a horse at a walk in an arena a few years ago, and suffered a devastating brain injury. I know people who have been killed riding because of how they came off the horse, or because of what happened immediately after they fell.
The fact that Ben left his dog home could say a couple things. 1) The weather was not great for the dog to be out. 2) Ben did not plan on being gone long, so he just decided to leave the dog home. 3) There was some physical reason the dog did not go along- dog was hurting, not feeling well, tired, etc.
I personally carry my cell phone with an app running that will tell my husband exactly where I am, and will send an emergency message if I stop moving and stay stationary for a set amount of time. BUT, that is when I am in an area with cell service. I carry a GPS SPOT transmitter for use in areas without cell service. It will pin point my location and allow me to send out an emergency text message IF I have satellite service and am able to physically send the message. Satellite service can be compromised if there is heavy leaf cover from trees.
I also carry a saddle bag with basic first aid gear for both me and the horse, a solar blanket, a headlamp and flashlight, a snack, etc., as well as water. It would be an issue though if separated from the horse because the saddlebag is tied to the saddle. My phone and SPOT transmitter are kept on my person.
While I am not personally familiar with the area Ben is in, I assume it is very rural and rugged, without cell service. If he was only planning on a short ride, he might not have used a saddle bag or even a SPOT transmitter, thinking he wouldn’t be gone long.
My fear is that the horse spooked, Ben came off and was injured or left unconscious. Concussions are extremely common in falls from horses and can lead to confusion. The results of this happening in an area like this ranch could be absolutely devastating.