abhege, we tell folks that an LGD isn't considered mature till they are two. But if this dog wasn't from protection type dogs, he might never "work" at that job. Also, if he wasn't raised with the goats, then he sees them as prey. Grabbing the back of the neck is a classic predator move. In a successful attack, the animal is bitten through the spinal column thus rendering it immobile and easy food. Most domestic dogs are not very good predators, but you don't want your goats as guinea pigs. I have seen many animals injured by the farm dogs.
We can't have chickens, for example, for whatever reason my LGDs think they don't belong and should die. They have no problem with ducks, geese, a peacock, occasional turkey or my guineas. But my original two LGDs came to me as adults and they hated chickens, now even though they are years gone, the tradition carries on. Sigh.
When I first got my Nubians, my existing dogs had a major problem with the idea of goats. I stepped in and got real ugly several times, but ultimately we decided it was easier to get new pups and raise them with the goats. I now have a year old and an eighteen month old pair with the goats. They will guard anything on the place but they are partial to their goats. We do set them up with the birds to get the point across that they are "MINE" and anyone who thinks different will depart from this earth. We have had a casualty or two, but they have since regretted it.
I would seek some advice from someone familiar with LGDs that can come out and offer on site advice. Or just keep the dog away from stock. It is interesting to me that you think the dog will run off. One of the most important traits of an LGD is the fact that they stay on the homestead.
Here is our "Sullygator"